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.
14 results
Sep 16, 2026NLnet Labs Unbound 1.12.0 up to and including 1.26.0 has a use-after-free vulnerability when compiled for DNS-over-HTTPs support with '--with-libnghttp2'.CVE-2026-82720 · Other software · NLnet Labs · reported by sep@nlnetlabs.nlMedium 5.9
NLnet Labs Unbound 1.12.0 up to and including 1.26.0 has a use-after-free vulnerability when compiled for DNS-over-HTTPs support with '--with-libnghttp2'. During failure code paths (i.e., RPZ drop query, jostle due to heavy traffic), a dropped DoH stream brings down the whole DoH session and does not account properly for other DoH streams in the same session. This leads to use-after-free in those code paths. If the prerequisites are satisfied (possible RPZ drop or heavy client traffic), a malicious actor can trigger the vulnerability with a single DoH connection and the appropriate traffic. Impact is limited as the reads are not user controlled and the use-after-free leads to early returns. However, a hardened allocator can catch the use-after-free and controllably terminate the process resulting to denial of service.
- Product
- Unbound
- What to do
- Apply the vendor’s update. The NVD record links to the advisory.
Aug 4, 2026A flaw in Node.js HTTP/2 handling allows `nghttp2_session_mem_send()` to be called re-entrantly while `nghttp2_session_mem_recv()` is executing, resulting in a CVE-2026-56848 · Other software · nodejs · reported by support@hackerone.comHigh 7.5
A flaw in Node.js HTTP/2 handling allows `nghttp2_session_mem_send()` to be called re-entrantly while `nghttp2_session_mem_recv()` is executing, resulting in a heap-use-after-free. This vulnerability affects Node.js **26.x**, **24.x**, and **22.x**.
- Product
- node
- What to do
- Apply the vendor’s update. The NVD record links to the advisory.
Jun 27, 2026nghttp2's nghttpx proxy through 1.69.0 forwards an HTTP/1.1 Upgrade request that also carries a Content-Length header and body onto reusable keep-alive backend CVE-2026-58055 · Other software · nghttp2 · reported by VulnCheckMedium 6.3
nghttp2's nghttpx proxy through 1.69.0 forwards an HTTP/1.1 Upgrade request that also carries a Content-Length header and body onto reusable keep-alive backend connections, re-adding the Upgrade and Connection headers while passing Content-Length verbatim. A backend that resolves the resulting ambiguous message in the attacker's favor enables HTTP request/response smuggling and cross-client response-queue poisoning.
- Product
- nghttp2
- What to do
- Apply the vendor’s update. The NVD record links to the advisory.
Mar 31, 2026When the early_acl_drop (earlyACLDrop in Lua) option is disabled (default is enabled) on a DNS over HTTPs frontend using the nghttp2 provider, the ACL check is CVE-2026-24029 · Other software · PowerDNS · reported by security@open-xchange.comMedium 6.5
When the early_acl_drop (earlyACLDrop in Lua) option is disabled (default is enabled) on a DNS over HTTPs frontend using the nghttp2 provider, the ACL check is skipped, allowing all clients to send DoH queries regardless of the configured ACL.
- Product
- DNSdist
- What to do
- Apply the vendor’s update. The NVD record links to the advisory.
Mar 18, 2026nghttp2 is an implementation of the Hypertext Transfer Protocol version 2 in C.CVE-2026-27135 · Other software · nghttp2 · reported by GitHubHigh 7.5
nghttp2 is an implementation of the Hypertext Transfer Protocol version 2 in C. Prior to version 1.68.1, the nghttp2 library stops reading the incoming data when user facing public API `nghttp2_session_terminate_session` or `nghttp2_session_terminate_session2` is called by the application. They might be called internally by the library when it detects the situation that is subject to connection error. Due to the missing internal state validation, the library keeps reading the rest of the data after one of those APIs is called. Then receiving a malformed frame that causes FRAME_SIZE_ERROR causes assertion failure. nghttp2 v1.68.1 adds missing state validation to avoid assertion failure. No known workarounds are available.
- Product
- nghttp2
- What to do
- Apply the vendor’s update. The NVD record links to the advisory.
Sep 18, 2025In some circumstances, when DNSdist is configured to use the nghttp2 library to process incoming DNS over HTTPS queries, an attacker might be able to cause a deCVE-2025-30187 · Other software · PowerDNS · reported by security@open-xchange.comLow 3.7
In some circumstances, when DNSdist is configured to use the nghttp2 library to process incoming DNS over HTTPS queries, an attacker might be able to cause a denial of service by crafting a DoH exchange that triggers an unbounded I/O read loop, causing an unexpected consumption of CPU resources.
- Product
- DNSdist
- What to do
- Apply the vendor’s update. The NVD record links to the advisory.
Full record and what to do →NVD recorddnsdist.orgopenwall.com
Apr 29, 2025When DNSdist is configured to provide DoH via the nghttp2 provider, an attacker can cause a denial of service by crafting a DoH exchange that triggers an illegaCVE-2025-30194 · Other software · PowerDNS · reported by security@open-xchange.comHigh 7.5
When DNSdist is configured to provide DoH via the nghttp2 provider, an attacker can cause a denial of service by crafting a DoH exchange that triggers an illegal memory access (double-free) and crash of DNSdist, causing a denial of service. The remedy is: upgrade to the patched 1.9.9 version. A workaround is to temporarily switch to the h2o provider until DNSdist has been upgraded to a fixed version. We would like to thank Charles Howes for bringing this issue to our attention.
- Product
- DNSdist
- What to do
- Apply the vendor’s update. The NVD record links to the advisory.
Full record and what to do →NVD recorddnsdist.orgopenwall.com
May 14, 2024When incoming DNS over HTTPS support is enabled using the nghttp2 provider, and queries are routed to a tcp-only or DNS over TLS backend, an attacker can triggeCVE-2024-25581 · Other software · PowerDNS · reported by security@open-xchange.comHigh 7.5
When incoming DNS over HTTPS support is enabled using the nghttp2 provider, and queries are routed to a tcp-only or DNS over TLS backend, an attacker can trigger an assertion failure in DNSdist by sending a request for a zone transfer (AXFR or IXFR) over DNS over HTTPS, causing the process to stop and thus leading to a Denial of Service. DNS over HTTPS is not enabled by default, and backends are using plain DNS (Do53) by default.
- Product
- DNSdist
- What to do
- Apply the vendor’s update. The NVD record links to the advisory.
Full record and what to do →NVD recordopenwall.comdnsdist.org
Apr 4, 2024HTTP/2 incoming headers exceeding the limit are temporarily buffered in nghttp2 in order to generate an informative HTTP 413 response.CVE-2024-27316 · Websites & servers · Apache Software Foundation · reported by security@apache.orgHigh 7.5
HTTP/2 incoming headers exceeding the limit are temporarily buffered in nghttp2 in order to generate an informative HTTP 413 response. If a client does not stop sending headers, this leads to memory exhaustion.
- Product
- Apache HTTP Server
- What to do
- Apply the vendor’s update. The NVD record links to the advisory.
Full record and what to do →NVD recordseclists.orgopenwall.com
Apr 4, 2024nghttp2 is an implementation of the Hypertext Transfer Protocol version 2 in C.CVE-2024-28182 · Other software · nghttp2 · reported by GitHubMedium 5.3
nghttp2 is an implementation of the Hypertext Transfer Protocol version 2 in C. The nghttp2 library prior to version 1.61.0 keeps reading the unbounded number of HTTP/2 CONTINUATION frames even after a stream is reset to keep HPACK context in sync. This causes excessive CPU usage to decode HPACK stream. nghttp2 v1.61.0 mitigates this vulnerability by limiting the number of CONTINUATION frames it accepts per stream. There is no workaround for this vulnerability.
- Product
- nghttp2
- What to do
- Apply the vendor’s update. The NVD record links to the advisory.
Full record and what to do →NVD recordopenwall.comgithub.com
Jun 3, 2020In nghttp2 before version 1.41.0, the overly large HTTP/2 SETTINGS frame payload causes denial of service.CVE-2020-11080 · Other software · nghttp2 · reported by GitHubLow 3.7
In nghttp2 before version 1.41.0, the overly large HTTP/2 SETTINGS frame payload causes denial of service. The proof of concept attack involves a malicious client constructing a SETTINGS frame with a length of 14,400 bytes (2400 individual settings entries) over and over again. The attack causes the CPU to spike at 100%. nghttp2 v1.41.0 fixes this vulnerability. There is a workaround to this vulnerability. Implement nghttp2_on_frame_recv_callback callback, and if received frame is SETTINGS frame and the number of settings entries are large (e.g., > 32), then drop the connection.
- Product
- nghttp2
- What to do
- Apply the vendor’s update. The NVD record links to the advisory.
Full record and what to do →NVD recordlists.opensuse.orggithub.com
Feb 6, 2020nghttp2 before 1.7.1 allows remote attackers to cause a denial of service (memory exhaustion).CVE-2016-1544 · Other software · nghttp2 · reported by cret@cert.orgLow 3.3
nghttp2 before 1.7.1 allows remote attackers to cause a denial of service (memory exhaustion).
- Product
- nghttp2
- What to do
- Apply the vendor’s update. The NVD record links to the advisory.
Full record and what to do →NVD recordlists.fedoraproject.orglists.fedoraproject.org
May 8, 2018nghttp2 version >= 1.10.0 and nghttp2 <= v1.31.0 contains an Improper Input Validation CWE-20 vulnerability in ALTSVC frame handling that can result in segmentaCVE-2018-1000168 · Other software · Nghttp2 · reported by MITREHigh 7.5
nghttp2 version >= 1.10.0 and nghttp2 <= v1.31.0 contains an Improper Input Validation CWE-20 vulnerability in ALTSVC frame handling that can result in segmentation fault leading to denial of service. This attack appears to be exploitable via network client. This vulnerability appears to have been fixed in >= 1.31.1.
- Product
- Nghttp2
- What to do
- Apply the vendor’s update. The NVD record links to the advisory.
Full record and what to do →NVD recordsecurityfocus.comaccess.redhat.com
Jan 12, 2016The idle stream handling in nghttp2 before 1.6.0 allows attackers to have unspecified impact via unknown vectors, aka a heap-use-after-free bug.CVE-2015-8659 · Computers, phones & browsers · Apple · reported by MITRECritical 10
The idle stream handling in nghttp2 before 1.6.0 allows attackers to have unspecified impact via unknown vectors, aka a heap-use-after-free bug.
- Product
- MAC OS X
- What to do
- Apply the vendor’s update. The NVD record links to the advisory.
Full record and what to do →NVD recordlists.apple.comlists.apple.com
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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