Inconsistent interpretation of HTTP requests in libevent - #VU136941
Published: July 6, 2026
Vulnerability identifier: #VU136941
CSH Severity: Medium
CVSS v4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N]
CVE-ID: N/A
CWE-ID: CWE-444
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to bypass access controls.
The vulnerability exists due to inconsistent interpretation of HTTP requests in evhttp_decode_uri_internal when processing percent-encoded URIs. A remote attacker can send a specially crafted request containing a %00 sequence to bypass access controls.
The issue arises because a decoded NUL byte can truncate the path for subsequent C string operations.
Affected software
libevent
Remediation
Install security update from vendor's website.
libevent - update to 2.1.13