ZDI-CAN-31036: ZDI-26-590: 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.
Other sources
This vulnerability allows remote attackers to execute arbitrary code on affected installations of libwebsockets. Authentication is not required to exploit this vulnerability. The ZDI has assigned a CVSS rating of 9.8. The following CVEs are assigned: CVE-2026-19773.
— ZDI
Affected Software
Event History
Frequently Asked Questions
What level of access does an attacker need to exploit this issue?
No authentication is required. A remote attacker can exploit the vulnerability to execute arbitrary code on an affected libwebsockets installation.
How severe is this vulnerability?
ZDI assigned this issue a CVSS score of 9.8, and the listed risk score is 95. Successful exploitation can result in remote code execution.