Updated 2 h ago

Vulnerability database

Every flaw the U.S. government’s cybersecurity agency (CISA) has confirmed attackers are using, plus the new WordPress plugin and theme bugs published each day, sorted by what they mean for a small business. We refresh it twice a day. If you see something your website or office runs, tell us.

1,762exploited flaws on CISA’s list

34added in the last 30 days

344new WordPress flaws this week

390,080entries in the database

24 results

Oct 21, 2026A reachable-assertion flaw in the HPACK header-compression decoder of the HTTP/2 (h2/gRPC) stack in Apache bRPC (version < 1.18.0) on all platforms allows a remCVE-2026-78048 · Websites & servers · Apache Software Foundation · reported by security@apache.org
A reachable-assertion flaw in the HPACK header-compression decoder of the HTTP/2 (h2/gRPC) stack in Apache bRPC (version < 1.18.0) on all platforms allows a remote attacker to crash the server process by sending a crafted sequence of HPACK headers, resulting in a denial of service. Root Cause: In src/brpc/details/hpack.cpp, IndexTable::Init sizes the dynamic-table ring buffer as num_headers = max_size / (32 + 2), i.e. it assumes a minimum table entry of 34 bytes (name >= 1 byte + value >= 1 byte + 32 bytes of overhead). However, RFC 7541 section 4.1 specifies that the minimum entry size is 33 bytes, because the value may be empty (name >= 1 byte + value == 0 + 32 bytes). For the default 4096-byte table this allocates only 120 slots (4096/34). Eviction in AddHeader is driven by byte usage (_max_size), not by slot count, so a peer can add 121 minimal 33-byte entries (121*33 = 3993 <= 4096) without triggering eviction. The 121st AddHeader then hits CHECK(!_header_queue.full()), which aborts the process. Affected Scenarios: Use a bRPC server that serves HTTP/2 or gRPC requests (e.g. via the h2 protocol) from an untrusted network. The malicious header block is processed during HPACK d
Product
Apache bRPC
What to do
Apply the vendor’s update. The NVD record links to the advisory.
Full record and what to do →NVD record lists.apache.org
Oct 21, 2026Uncontrolled recursion in the HTTP/2 HPACK decoder in Apache bRPC before 1.18.0 allows remote attackers to cause denial of service by sending a crafted HTTP/2 hCVE-2026-54425 · Websites & servers · Apache Software Foundation · reported by security@apache.org
Uncontrolled recursion in the HTTP/2 HPACK decoder in Apache bRPC before 1.18.0 allows remote attackers to cause denial of service by sending a crafted HTTP/2 header block containing many consecutive Dynamic Table Size Update entries. Each update was decoded by recursively invoking the HPACK decoder, which could exhaust the thread stack before a header field or end of input was reached. Root Cause: The bRPC HPACK decoder recursively decoded the next entry after processing a Dynamic Table Size Update. The decoder did not bound the recursion depth, so a long sequence of update entries could consume excessive stack space. Affected Scenarios: Use bRPC with the built-in HTTP/2 implementation to accept HTTP/2 traffic from an untrusted network. How to Fix: 1. Upgrade bRPC to version 1.18.0, which fixes this issue. 2. Apply this patch: https://github.com/apache/brpc/pull/3343 Note: The fix changes HPACK Dynamic Table Size Update decoding to use iterative parsing instead of recursive parsing.
Product
Apache bRPC
What to do
Apply the vendor’s update. The NVD record links to the advisory.
Full record and what to do →NVD record lists.apache.org
Oct 8, 2026HTTP/2 servers could end up crashing due to inadvertently modifying its HPACK encoder concurrently.CVE-2026-97032 · Other software · Go standard library · reported by security@golang.orgHigh 7.5
HTTP/2 servers could end up crashing due to inadvertently modifying its HPACK encoder concurrently. This happens because the server modifies the HPACK encoder from two goroutines without synchronization: one uses the encoder to encode a HEADERS frame as part of a response sent to a client and the other modifies the encoder's table size when handling a SETTINGS frame containing SETTINGS_HEADER_TABLE_SIZE that a client sends. A malicious client can repeatedly send a request while changing the header table size to crash the server.
Product
net/http
What to do
Apply the vendor’s update. The NVD record links to the advisory.
Full record and what to do →NVD record go.dev go.dev
Sep 23, 2026hpack is an HTTP/2 Header Encoding for Python.CVE-2026-59980 · Other software · python-hyper · reported by GitHubMedium 6.3
hpack is an HTTP/2 Header Encoding for Python. Prior to version 4.2.0, unbounded variable integer decoding can cause run-away computation on malformed input leading to O(n^2) runtime, effectively blocking further processing with large enough unsanitized input. A fix is available in python-hyper/hpack v4.2.0 to restricted variable integer decoding to uint32 to prevent run-away computation. As a workaround, sanitize input to hpack decoder for long sequences of `0xFF` values to prevent malicious use.
Product
hpack
What to do
Apply the vendor’s update. The NVD record links to the advisory.
Full record and what to do →NVD record cs.opensource.google docs.rs
Sep 18, 2026A flaw was found in Netty's HTTP/2 HpackEncoder.CVE-2026-93492 · Other software · Red Hat · reported by Red HatMedium 5.3
A flaw was found in Netty's HTTP/2 HpackEncoder. A remote attacker can exploit this by sending HTTP/2 SETTINGS frames with a very large MAX_HEADER_TABLE_SIZE. This causes the HpackEncoder to store an excessive number of unique headers, leading to increased CPU usage and memory consumption, ultimately resulting in a Denial of Service (DoS).
Product
Red Hat Build of Debezium 3.6
What to do
Apply the vendor’s update. The NVD record links to the advisory.
Full record and what to do →NVD record access.redhat.com access.redhat.com
Sep 15, 2026libwebsockets HTTP/2 HPACK Path Header Parsing Out-Of-Bounds Write Remote Code Execution Vulnerability.CVE-2026-19773 · Other software · libwebsockets · reported by zdi-disclosures@trendmicro.comCritical 9.8
libwebsockets HTTP/2 HPACK Path Header Parsing Out-Of-Bounds Write Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installations of libwebsockets. Authentication is not required to exploit this vulnerability. The specific flaw exists within the parsing of HTTP/2 HPACK path header. The issue results from the lack of proper validation of user-supplied data, which can result in a write past the end of an allocated buffer. An attacker can leverage this vulnerability to execute code in the context of the current process. Was ZDI-CAN-31036.
Product
libwebsockets
What to do
Apply the vendor’s update. The NVD record links to the advisory.
Full record and what to do →NVD record github.com zerodayinitiative.com
Jul 29, 2026Apache Traffic Server updates the HTTP/2 HPACK dynamic table before confirming the header block encoded successfully, so an encode failure leaves the encoder ouCVE-2026-65100 · Websites & servers · Apache Software Foundation · reported by security@apache.orgMedium 6.3
Apache Traffic Server updates the HTTP/2 HPACK dynamic table before confirming the header block encoded successfully, so an encode failure leaves the encoder out of sync with the peer decoder and corrupts subsequent header blocks on the connection. This issue affects Apache Traffic Server: from 8.0.0 through 8.1.11, from 9.0.0 through 9.2.14, from 10.0.0 through 10.1.3. Users are recommended to upgrade to version 9.2.15 or 10.1.4, which fix the issue.
Product
Apache Traffic Server
What to do
Apply the vendor’s update. The NVD record links to the advisory.
Full record and what to do →NVD record lists.apache.org
Jul 29, 2026Apache Traffic Server mishandles integers while decoding HPACK/XPACK headers, corrupting memory.CVE-2026-58152 · Websites & servers · Apache Software Foundation · reported by security@apache.orgMedium 6.9
Apache Traffic Server mishandles integers while decoding HPACK/XPACK headers, corrupting memory. This issue affects Apache Traffic Server: from 8.0.0 through 8.1.11, from 9.0.0 through 9.2.14, from 10.0.0 through 10.1.3. Users are recommended to upgrade to version 9.2.15 or 10.1.4, which fix the issue.
Product
Apache Traffic Server
What to do
Apply the vendor’s update. The NVD record links to the advisory.
Full record and what to do →NVD record lists.apache.org
Jul 6, 2026Inefficient Algorithmic Complexity vulnerability in elixir-mint hpax allows unauthenticated denial-of-service via unbounded HPACK integer decoding.CVE-2026-58226 · Other software · elixir-mint · reported by 6b3ad84c-e1a6-4bf7-a703-f496b71e49dbHigh 8.7
Inefficient Algorithmic Complexity vulnerability in elixir-mint hpax allows unauthenticated denial-of-service via unbounded HPACK integer decoding. hpax decodes HPACK variable-length integers with no upper bound on the decoded value or the number of continuation octets. 'Elixir.HPAX.Types':decode_remaining_integer/3 accumulates the integer as int + (value <<< m), shifting by 7 more bits for each continuation octet and stopping only on a terminating octet or truncated input, never because the integer grew too large. Because BEAM integers are arbitrary precision, a run of N continuation octets builds an O(N)-bit bignum and re-adds into an ever-larger bignum on each step, so the total decoding cost is superlinear (about O(N^2)). An unauthenticated attacker who can send an HTTP/2 header block to a server using this decoder (reached through the 'Elixir.HPAX':decode/2 entry point) can supply a small header block that forces a large, attacker-controlled amount of CPU (and transient memory), a denial-of-service amplification. This issue affects hpax from 0.1.1 before 1.0.4.
Product
hpax
What to do
Apply the vendor’s update. The NVD record links to the advisory.
Full record and what to do →NVD record cna.erlef.org github.com
Jul 1, 2026Allocation of resources without limits or throttling in the HTTP/2 HPACK decoder in Apache HttpComponents Core (5.4.2 and earlier, 5.5-beta1 and earlier) allowsCVE-2026-54428 · Websites & servers · Apache Software Foundation · reported by security@apache.orgHigh 7.5
Allocation of resources without limits or throttling in the HTTP/2 HPACK decoder in Apache HttpComponents Core (5.4.2 and earlier, 5.5-beta1 and earlier) allows an remote attacker to cause a denial of service through memory exhaustion by sending oversized compressed header blocks before the HTTP/2 SETTINGS acknowledgement causes the configured header list size limit to be applied.
Product
Apache HttpComponents Core
What to do
Apply the vendor’s update. The NVD record links to the advisory.
Full record and what to do →NVD record lists.apache.org openwall.com
Jun 18, 2026HAProxy through 3.4.0, fixed in commit 9a6d1fe, contains a null pointer dereference vulnerability in hpack_dht_insert() within src/hpack-tbl.c that fails to vaCVE-2026-55204 · Other software · haproxy · reported by VulnCheckHigh 8.7
HAProxy through 3.4.0, fixed in commit 9a6d1fe, contains a null pointer dereference vulnerability in hpack_dht_insert() within src/hpack-tbl.c that fails to validate the return value of hpack_dht_defrag() when the memory pool is exhausted. An attacker can trigger HPACK dynamic table insertions under memory pressure to dereference a NULL pointer and crash HAProxy worker processes, causing denial of service.
Product
haproxy
What to do
Apply the vendor’s update. The NVD record links to the advisory.
Full record and what to do →NVD record github.com vulncheck.com
Jun 12, 2026Improper handling of HPACK dynamic table size updates in the AWS Common Runtime aws-c-http library might allow a remote threat actor operating a server to causeCVE-2026-12043 · Other software · AWS · reported by ff89ba41-3aa1-4d27-914a-91399e9639e5High 8.7
Improper handling of HPACK dynamic table size updates in the AWS Common Runtime aws-c-http library might allow a remote threat actor operating a server to cause memory corruption on a connecting client application, potentially leading to arbitrary code execution, via a crafted sequence of HTTP/2 HEADERS frames. To remediate this issue, users should upgrade to aws-c-http version 0.11.0.
Product
aws-c-http
What to do
Apply the vendor’s update. The NVD record links to the advisory.
Full record and what to do →NVD record aws.amazon.com github.com
Jan 20, 2026A malformed `HTTP/2 HEADERS` frame with oversized, invalid `HPACK` data can cause Node.js to crash by triggering an unhandled `TLSSocket` error `ECONNRESET`.CVE-2025-59465 · Other software · nodejs · reported by support@hackerone.comHigh 7.5
A malformed `HTTP/2 HEADERS` frame with oversized, invalid `HPACK` data can cause Node.js to crash by triggering an unhandled `TLSSocket` error `ECONNRESET`. Instead of safely closing the connection, the process crashes, enabling a remote denial of service. This primarily affects applications that do not attach explicit error handlers to secure sockets, for example: ``` server.on('secureConnection', socket => { socket.on('error', err => { console.log(err) }) }) ```
Product
node
What to do
Apply the vendor’s update. The NVD record links to the advisory.
Full record and what to do →NVD record nodejs.org access.redhat.com
Aug 6, 2024It's possible for a gRPC client communicating with a HTTP/2 proxy to poison the HPACK table between the proxy and the backend such that other clients see failedCVE-2024-7246 · Computers, phones & browsers · Google · reported by cve-coordination@google.comMedium 6.3
It's possible for a gRPC client communicating with a HTTP/2 proxy to poison the HPACK table between the proxy and the backend such that other clients see failed requests. It's also possible to use this vulnerability to leak other clients HTTP header keys, but not values. This occurs because the error status for a misencoded header is not cleared between header reads, resulting in subsequent (incrementally indexed) added headers in the first request being poisoned until cleared from the HPACK table. Please update to a fixed version of gRPC as soon as possible. This bug has been fixed in 1.58.3, 1.59.5, 1.60.2, 1.61.3, 1.62.3, 1.63.2, 1.64.3, 1.65.4.
Product
gRPC
What to do
Apply the vendor’s update. The NVD record links to the advisory.
Full record and what to do →NVD record github.com
Aug 9, 2023gRPC contains a vulnerability that allows hpack table accounting errors could lead to unwanted disconnects between clients and servers in exceptional cases/ ThrCVE-2023-33953 · Computers, phones & browsers · Google · reported by cve-coordination@google.comHigh 7.5
gRPC contains a vulnerability that allows hpack table accounting errors could lead to unwanted disconnects between clients and servers in exceptional cases/ Three vectors were found that allow the following DOS attacks: - Unbounded memory buffering in the HPACK parser - Unbounded CPU consumption in the HPACK parser The unbounded CPU consumption is down to a copy that occurred per-input-block in the parser, and because that could be unbounded due to the memory copy bug we end up with an O(n^2) parsing loop, with n selected by the client. The unbounded memory buffering bugs: - The header size limit check was behind the string reading code, so we needed to first buffer up to a 4 gigabyte string before rejecting it as longer than 8 or 16kb. - HPACK varints have an encoding quirk whereby an infinite number of 0’s can be added at the start of an integer. gRPC’s hpack parser needed to read all of them before concluding a parse. - gRPC’s metadata overflow check was performed per frame, so that the following sequence of frames could cause infinite buffering: HEADERS: containing a: 1 CONTINUATION: containing a: 2 CONTINUATION: containing a: 3 etc…
Product
gRPC
What to do
Apply the vendor’s update. The NVD record links to the advisory.
Full record and what to do →NVD record cloud.google.com cloud.google.com
Jun 9, 2023When gRPC HTTP2 stack raised a header size exceeded error, it skipped parsing the rest of the HPACK frame.CVE-2023-32731 · Computers, phones & browsers · Google · reported by cve-coordination@google.comHigh 7.4
When gRPC HTTP2 stack raised a header size exceeded error, it skipped parsing the rest of the HPACK frame. This caused any HPACK table mutations to also be skipped, resulting in a desynchronization of HPACK tables between sender and receiver. If leveraged, say, between a proxy and a backend, this could lead to requests from the proxy being interpreted as containing headers from different proxy clients - leading to an information leak that can be used for privilege escalation or data exfiltration. We recommend upgrading beyond the commit contained in https://github.com/grpc/grpc/pull/33005 https://github.com/grpc/grpc/pull/33005
Product
gRPC
What to do
Apply the vendor’s update. The NVD record links to the advisory.
Full record and what to do →NVD record github.com github.com
Feb 28, 2023A maliciously crafted HTTP/2 stream could cause excessive CPU consumption in the HPACK decoder, sufficient to cause a denial of service from a small number of sCVE-2022-41723 · Other software · Go standard library · reported by security@golang.orgHigh 7.5
A maliciously crafted HTTP/2 stream could cause excessive CPU consumption in the HPACK decoder, sufficient to cause a denial of service from a small number of small requests.
Product
net/http
What to do
Apply the vendor’s update. The NVD record links to the advisory.
Full record and what to do →NVD record go.dev go.dev
Feb 9, 2022A program using swift-nio-http2 is vulnerable to a denial of service attack, caused by a network peer sending a specially crafted HPACK-encoded header block.CVE-2022-24667 · Other software · Swift Project · reported by cve@forums.swift.orgHigh 7.5
A program using swift-nio-http2 is vulnerable to a denial of service attack, caused by a network peer sending a specially crafted HPACK-encoded header block. This attack affects all swift-nio-http2 versions from 1.0.0 to 1.19.1. There are a number of implementation errors in the parsing of HPACK-encoded header blocks that allow maliciously crafted HPACK header blocks to cause crashes in processes using swift-nio-http2. Each of these crashes is triggered instead of an integer overflow. A malicious HPACK header block could be sent on any of the HPACK-carrying frames in a HTTP/2 connection (HEADERS and PUSH_PROMISE), at any position. Sending a HPACK header block does not require any special permission, so any HTTP/2 connection peer may send one. For clients, this means any server to which they connect may launch this attack. For servers, anyone they allow to connect to them may launch such an attack. The attack is low-effort: it takes very little resources to send an appropriately crafted field block. The impact on availability is high: receiving a frame carrying this field block immediately crashes the server, dropping all in-flight connections and causing the service to need to rest
Product
SwiftNIO HTTP2
What to do
Apply the vendor’s update. The NVD record links to the advisory.
Full record and what to do →NVD record github.com github.com
Apr 2, 2020In hpack_dht_insert in hpack-tbl.c in the HPACK decoder in HAProxy 1.8 through 2.x before 2.1.4, a remote attacker can write arbitrary bytes around a certain loCVE-2020-11100 · Other software · Haproxy · reported by MITREHigh 8.8
In hpack_dht_insert in hpack-tbl.c in the HPACK decoder in HAProxy 1.8 through 2.x before 2.1.4, a remote attacker can write arbitrary bytes around a certain location on the heap via a crafted HTTP/2 request, possibly causing remote code execution.
Product
Haproxy
What to do
Apply the vendor’s update. The NVD record links to the advisory.
Full record and what to do →NVD record lists.opensuse.org packetstormsecurity.com
Dec 4, 2019In the course of decompressing HPACK inside the HTTP2 protocol, an unexpected sequence of header table resize operations can place the header table into a corruCVE-2019-11940 · Other software · Facebook · reported by cve-assign@fb.comCritical 9.8
In the course of decompressing HPACK inside the HTTP2 protocol, an unexpected sequence of header table resize operations can place the header table into a corrupted state, leading to a use-after-free condition and undefined behavior. This issue affects Proxygen from v0.29.0 until v2017.04.03.00.
Product
Proxygen
What to do
Apply the vendor’s update. The NVD record links to the advisory.
Full record and what to do →NVD record github.com facebook.com
Sep 21, 2018A flaw was discovered in the HPACK decoder of HAProxy, before 1.8.14, that is used for HTTP/2.CVE-2018-14645 · Other software · [UNKNOWN] · reported by Red HatHigh 7.5
A flaw was discovered in the HPACK decoder of HAProxy, before 1.8.14, that is used for HTTP/2. An out-of-bounds read access in hpack_valid_idx() resulted in a remote crash and denial of service.
Product
haproxy
What to do
Apply the vendor’s update. The NVD record links to the advisory.
Full record and what to do →NVD record access.redhat.com access.redhat.com
Jul 25, 2018F5 BIG-IP 13.0.0-13.1.0.5, 12.1.0-12.1.3.5, or 11.6.0-11.6.3.1 virtual servers with HTTP/2 profiles enabled are vulnerable to "HPACK Bomb".CVE-2018-5530 · Network & remote access · F5 Networks, Inc. · reported by f5sirt@f5.comHigh 7.5
F5 BIG-IP 13.0.0-13.1.0.5, 12.1.0-12.1.3.5, or 11.6.0-11.6.3.1 virtual servers with HTTP/2 profiles enabled are vulnerable to "HPACK Bomb".
Product
BIG-IP (LTM, AAM, AFM, Analytics, APM, ASM, Edge Gateway, PEM, WebSafe)
What to do
Apply the vendor’s update. The NVD record links to the advisory.
Full record and what to do →NVD record securityfocus.com support.f5.com
Apr 17, 2017Apache Traffic Server 6.0.0 to 6.2.0 are affected by an HPACK Bomb Attack.CVE-2016-5396 · Websites & servers · Apache Software Foundation · reported by security@apache.orgHigh 7.5
Apache Traffic Server 6.0.0 to 6.2.0 are affected by an HPACK Bomb Attack.
Product
Apache Traffic Server
What to do
Apply the vendor’s update. The NVD record links to the advisory.
Full record and what to do →NVD record securityfocus.com securitytracker.com
Jan 10, 2017A HTTP/2 implementation built using any version of the Python HPACK library between v1.0.0 and v2.2.0 could be targeted for a denial of service attack, specificCVE-2016-6581 · Other software · Python · reported by MITREHigh 7.5
A HTTP/2 implementation built using any version of the Python HPACK library between v1.0.0 and v2.2.0 could be targeted for a denial of service attack, specifically a so-called "HPACK Bomb" attack. This attack occurs when an attacker inserts a header field that is exactly the size of the HPACK dynamic header table into the dynamic header table. The attacker can then send a header block that is simply repeated requests to expand that field in the dynamic table. This can lead to a gigantic compression ratio of 4,096 or better, meaning that 16kB of data can decompress to 64MB of data on the target machine.
Product
Hpack
What to do
Apply the vendor’s update. The NVD record links to the advisory.
Full record and what to do →NVD record securityfocus.com python-hyper.org

Where this comes from: the exploited list is CISA’s Known Exploited Vulnerabilities catalog. Everything else is the whole National Vulnerability Database, where each record is published by the team that found the bug (Wordfence, Patchstack, WPScan, the vendors themselves and others); we show who. Exploit odds are FIRST’s EPSS, updated daily. Titles and categories are ours, so check the linked record before acting on a detail. For a write-up of the big ones, see our advisories. Every vendor, and every WordPress plugin and theme with a recorded flaw, also has its own page. All of it is free to reuse as JSON, CSV or RSS.

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