CVE-2026-19773

NameCVE-2026-19773
Descriptionlibwebsockets 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.
SourceCVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
ReferencesDSA-6529-1
Debian Bugs1149178

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
libwebsockets (PTS)bookworm4.1.6-3vulnerable
trixie4.3.5-1+deb13u2vulnerable
trixie (security)4.3.5-1+deb13u3fixed
forky, sid4.3.5-7fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
libwebsocketssourcetrixie4.3.5-1+deb13u3DSA-6529-1
libwebsocketssource(unstable)4.3.5-71149178

Notes

https://www.zerodayinitiative.com/advisories/ZDI-26-590/
Fixed by: https://github.com/warmcat/libwebsockets/commit/824151862f37bc72f46d9a3e01d5b9408d313a0b (v5.0.0)

Search for package or bug name: Reporting problems