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.
8 results
Oct 5, 2026In Progress® Telerik® Fiddler® Classic for Windows, versions prior to v6.0.20262.10021, the integrity check applied to the external helper tools launched by theCVE-2026-77805 · Other software · Progress Software · reported by security@progress.comHigh 7.9
In Progress® Telerik® Fiddler® Classic for Windows, versions prior to v6.0.20262.10021, the integrity check applied to the external helper tools launched by the application is insufficient. Before executing a helper tool, the application only verifies that the file carries a valid Authenticode signature whose certificate subject name matches a broad allow list of publisher name fragments, rather than verifying that the file is the specific executable shipped with that version of the product. A local threat actor with low privileges who replaces one of these helper executables with any other validly signed binary from an allow-listed publisher can cause the substituted binary to be executed by the application, including with Administrator privileges for the tools that request elevation, resulting in privilege escalation and execution of unintended code. Successful exploitation requires the user to launch the affected external tool and to approve the elevation prompt without noticing that it refers to a different executable.
- Product
- Progress® Telerik® Fiddler® Classic
- What to do
- Apply the vendor’s update. The NVD record links to the advisory.
Oct 5, 2026In Progress® Telerik® Fiddler® Classic for Windows, versions prior to v6.0.20262.10021, a time-of-check time-of-use (TOCTOU) race condition exists in the instalCVE-2026-77804 · Other software · Progress Software · reported by security@progress.comMedium 6.6
In Progress® Telerik® Fiddler® Classic for Windows, versions prior to v6.0.20262.10021, a time-of-check time-of-use (TOCTOU) race condition exists in the installation of the HTTPS interception root certificate into the Local Computer certificate store. Fiddler writes the certificate to a temporary file in a user-writable location and then launches the external TrustCert helper application, which elevates and imports the certificate from that file. A local threat actor with low privileges who replaces the temporary file between the time it is written and the time the elevated helper reads it can cause an attacker-supplied root certificate to be installed in the Local Computer Trusted Root Certification Authorities store, enabling subsequent interception and modification of TLS-protected traffic on the machine. Successful exploitation requires the user to initiate the certificate trust operation and approve the elevation prompt.
- Product
- Progress® Telerik® Fiddler® Classic
- What to do
- Apply the vendor’s update. The NVD record links to the advisory.
Oct 5, 2026In Progress® Telerik® Fiddler® Classic for Windows, versions prior to v6.0.20262.10021, front-end request desynchronization is possible in the proxy request forCVE-2026-77803 · Other software · Progress Software · reported by security@progress.comLow 3.6
In Progress® Telerik® Fiddler® Classic for Windows, versions prior to v6.0.20262.10021, front-end request desynchronization is possible in the proxy request forwarding component. A request that contains both a Content-Length and a Transfer-Encoding header is forwarded with both headers present, while Fiddler frames the body using Transfer-Encoding only. The remaining bytes on the reused client connection are then parsed as a separate pipelined request, so a local threat actor with low privileges can cause a single malformed request to be split into two requests forwarded to the origin server and receive an additional smuggled response, without requiring a vulnerable server.
- Product
- Progress® Telerik® Fiddler® Classic
- What to do
- Apply the vendor’s update. The NVD record links to the advisory.
Oct 5, 2026In Progress® Telerik® Fiddler® Classic for Windows, versions prior to v6.0.20262.10021, HTTP request smuggling is possible in the proxy request forwarding compoCVE-2026-77802 · Other software · Progress Software · reported by security@progress.comMedium 6.3
In Progress® Telerik® Fiddler® Classic for Windows, versions prior to v6.0.20262.10021, HTTP request smuggling is possible in the proxy request forwarding component. Requests containing multiple Content-Length headers with conflicting values are forwarded verbatim to the origin server, while Fiddler frames the request body using only the first Content-Length value. A local threat actor with low privileges who is able to send requests through the same Fiddler proxy instance as another user can exploit this desynchronization against a non-RFC-9110-compliant origin server that keeps the connection alive to smuggle an additional request. Because Fiddler returns the server connection to its pipe pool after reading only the first response, the unread smuggled response remains buffered on the socket and is served to the next session that reuses that connection, allowing the attacker to poison responses delivered to other users and to obtain responses intended for them.
- Product
- Progress® Telerik® Fiddler® Classic
- What to do
- Apply the vendor’s update. The NVD record links to the advisory.
Sep 29, 2026Missing authentication in the local .NET backend (Fiddler.WebUi) of Progress Software Fiddler Everywhere 8.0.2 allows a local unauthenticated attacker to mint OCVE-2026-86158 · Other software · Progress Software · reported by security@progress.comHigh 7.7
Missing authentication in the local .NET backend (Fiddler.WebUi) of Progress Software Fiddler Everywhere 8.0.2 allows a local unauthenticated attacker to mint OAuth tokens and read the machine-in-the-middle root certificate through an unauthenticated localhost HTTP and SignalR RPC channel.
- Product
- Progress® Telerik® Fiddler® Everywhere
- What to do
- Apply the vendor’s update. The NVD record links to the advisory.
Sep 29, 2026Exposure of privileged IPC functionality in Progress Telerik Fiddler Everywhere before version 8.2.0 allows a local, low-privileged attacker who can modify applCVE-2026-86157 · Other software · Progress Software · reported by security@progress.comMedium 5.6
Exposure of privileged IPC functionality in Progress Telerik Fiddler Everywhere before version 8.2.0 allows a local, low-privileged attacker who can modify application launch parameters and persuade a user to start the application to replace the application UI or settings with attacker-controlled content. Successful exploitation could result in disclosure of OAuth authentication tokens, execution of locally accessible programs, or unauthorized modification of application-generated configuration files.
- Product
- Progress® Telerik® Fiddler® Everywhere
- What to do
- Apply the vendor’s update. The NVD record links to the advisory.
Nov 5, 2020Telerik Fiddler through 5.0.20202.18177 allows attackers to execute arbitrary programs via a hostname with a trailing space character, followed by --utility-andCVE-2020-13661 · Other software · Telerik · reported by MITREHigh 8.8
Telerik Fiddler through 5.0.20202.18177 allows attackers to execute arbitrary programs via a hostname with a trailing space character, followed by --utility-and-browser --utility-cmd-prefix= and the pathname of a locally installed program. The victim must interactively choose the Open On Browser option. Fixed in version 5.0.20204.
- Product
- Fiddler
- What to do
- Apply the vendor’s update. The NVD record links to the advisory.
Full record and what to do →NVD recordnagenrauft-consulting.comtelerik.com
Jun 3, 2019Telerik Fiddler v5.0.20182.28034 doesn't verify the hash of EnableLoopback.exe before running it, which could lead to code execution or local privilege escalatiCVE-2019-12097 · Other software · Progress · reported by MITREHigh 7.8
Telerik Fiddler v5.0.20182.28034 doesn't verify the hash of EnableLoopback.exe before running it, which could lead to code execution or local privilege escalation by replacing the original EnableLoopback.exe.
- Product
- Fiddler
- What to do
- Apply the vendor’s update. The NVD record links to the advisory.
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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