CVE-2026-19773

EUVD-2026-79130
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.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
NISTPrimary
9.8 CRITICAL
NETWORK
LOW
NONE
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Awaiting analysis
This vulnerability is currently awaiting analysis.
Base Score
CVSS 3.x
EPSS Score
Percentile: 50.94%
Debian logo
Debian Releases
Debian Product
Codename
libwebsockets
bookworm
vulnerable
forky
4.3.5-7
fixed
sid
4.3.5-7
fixed
trixie
vulnerable
trixie (security)
4.3.5-1+deb13u3
fixed
Ubuntu logo
Ubuntu Releases
Ubuntu Product
Codename
libwebsockets
bionic
Fixed 2.0.3-3ubuntu0.1~esm1
released
focal
Fixed 3.2.1-3ubuntu0.1~esm3
released
jammy
Fixed 4.0.20-2ubuntu1.1+esm2
released
noble
Fixed 4.3.3-1.1ubuntu0.1~esm3
released
resolute
Fixed 4.3.5-3ubuntu1.2+esm1
released
xenial
Fixed 1.7.1-1ubuntu0.1~esm1
released