CVE-2026-40935: WWBN/AVideo has CAPTCHA Bypass via Attacker-Controlled Length Parameter and Missing Token Invalidation on Failure
WWBN AVideo is an open source video platform. In versions 29.0 and prior, objects/getCaptcha.php accepts the CAPTCHA length (ql) directly from the query string with no clamping or sanitization, letting any unauthenticated client force the server to generate a 1-character CAPTCHA word. Combined with a case-insensitive strcasecmp comparison over a ~33-character alphabet and the fact that failed validations do NOT consume the stored session token, an attacker can trivially brute-force the CAPTCHA on any endpoint that relies on Captcha::validation() (user registration, password recovery, contact form, etc.) in at most ~33 requests per session. Commit bf1c76989e6a9054be4f0eb009d68f0f2464b453 contains a fix.
Affected Software
Remediation
Event History
Frequently Asked Questions
What is the severity of CVE-2026-40935?
CVE-2026-40935 has a medium severity rating due to its potential for security bypass involving CAPTCHA.
How do I fix CVE-2026-40935?
To fix CVE-2026-40935, upgrade to a version of WWBN AVideo later than 29.0 to ensure proper handling of the CAPTCHA functionality.
What does CVE-2026-40935 involve?
CVE-2026-40935 involves a CAPTCHA bypass vulnerability that can be exploited through an attacker-controlled length parameter.
Which versions of AVideo are affected by CVE-2026-40935?
AVideo versions up to and including 29.0 are affected by CVE-2026-40935.
Is there a known exploit for CVE-2026-40935?
Yes, CVE-2026-40935 can be exploited due to missing token invalidation on failure, allowing attackers to bypass CAPTCHA protections.