Resource exhaustion in OPNsense - #VU139363
Published: July 26, 2026
Vulnerability identifier: #VU139363
CSH Severity: Medium
CVSS v4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N]
CVE-ID: N/A
CWE-ID: CWE-400
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to uncontrolled resource consumption in the WebGUI lighttpd listener when buffering request bodies before authentication and CSRF validation. A remote attacker can send one or more large POST requests to cause a denial of service.
The listener accepts request bodies up to 2 GiB and uses temporary files on the root filesystem before passing requests to PHP/FastCGI.
Affected software
OPNsense
Remediation
Install security update from vendor's website.
OPNsense - update to 26.7.1