by Kastro
Paper/Archive/CVE-2026-19773

CVE-2026-19773

libwebsockets libwebsockets — libwebsockets HTTP/2 HPACK Path Header Parsing Out-Of-Bounds Write Remote Code Execution Vulnerability

EPSS 0.6%CVSS 9.8
critical.is priorityof 100
40
CVSS 9.8 (CNA)9.8 / 10 × 3029.4Not in CISA KEV+300.0EPSS percentile 51.0.510 × 2010.2No public exploit+100.0SSVC exploitation: none+100.0
Description · from the CVE record

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.

Affected

ProductAffectedFixed inSource
libwebsocketsb4b5aed3903eaff09cd76a410f69bbe5dff66f8e–CNA

Scores by source

zdi (CNA)9.8CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CISA ADPSSVCExploitation: none · Automatable: yes · Technical impact: total

References

refzerodayinitiative.com/advisories/ZDI-26-590advisorygithub.com/warmcat/libwebsockets/commit/824151862f37bc72f46d9a3e01d5b9408d313a0b