CVE-2026-19773

Critical

Description

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.

SeverityCritical

CVSS9.8

Exploit probability—

ProductLibwebsockets

PublishedSep 15, 2026

First seenSep 15, 2026

Weakness typeCWE-787Out-of-bounds write

How to fix

Vendor advisories

github.com/warmcat/libwebsockets/commit/824151862f37bc72f46d9a3e01d5b9408d313a0b

Affected products

Product	Affected versions	Fixed in
libwebsockets libwebsockets	b4b5aed3903eaff09cd76a410f69bbe5dff66f8e	—

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