CVE-2026-40935: CWE-804: Guessable CAPTCHA in WWBN AVideo
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.
AI Analysis
Technical Summary
CVE-2026-40935 affects WWBN AVideo (<= 29.0) where the CAPTCHA length parameter ('ql') in objects/getCaptcha.php can be manipulated by unauthenticated clients to force generation of a single-character CAPTCHA. Due to the case-insensitive comparison over a ~33-character alphabet and the failure to invalidate session tokens on failed CAPTCHA attempts, attackers can brute-force the CAPTCHA in approximately 33 tries per session. This impacts any endpoint using Captcha::validation(), including user registration, password recovery, and contact forms. The vulnerability is classified as CWE-804 (Improper Access Control). A code commit has been identified that fixes the issue, but no official patch or advisory details are available.
Potential Impact
The vulnerability allows an unauthenticated attacker to bypass CAPTCHA protections with minimal effort, potentially enabling automated abuse of user registration, password recovery, and contact forms. This could lead to increased spam, account enumeration, or other automated attacks relying on CAPTCHA bypass. There is no direct confidentiality or availability impact reported.
Mitigation Recommendations
A fix is referenced in commit bf1c76989e6a9054be4f0eb009d68f0f2464b453, indicating that a patch is available in the source code repository. Users of WWBN AVideo should update to a version including this commit or apply the fix manually. Since no official vendor advisory or patch release is provided, verify the fix status with the vendor or source repository. Until patched, consider implementing additional CAPTCHA validation controls or rate limiting on affected endpoints.
CVE-2026-40935: CWE-804: Guessable CAPTCHA in WWBN AVideo
Description
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.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-40935 affects WWBN AVideo (<= 29.0) where the CAPTCHA length parameter ('ql') in objects/getCaptcha.php can be manipulated by unauthenticated clients to force generation of a single-character CAPTCHA. Due to the case-insensitive comparison over a ~33-character alphabet and the failure to invalidate session tokens on failed CAPTCHA attempts, attackers can brute-force the CAPTCHA in approximately 33 tries per session. This impacts any endpoint using Captcha::validation(), including user registration, password recovery, and contact forms. The vulnerability is classified as CWE-804 (Improper Access Control). A code commit has been identified that fixes the issue, but no official patch or advisory details are available.
Potential Impact
The vulnerability allows an unauthenticated attacker to bypass CAPTCHA protections with minimal effort, potentially enabling automated abuse of user registration, password recovery, and contact forms. This could lead to increased spam, account enumeration, or other automated attacks relying on CAPTCHA bypass. There is no direct confidentiality or availability impact reported.
Mitigation Recommendations
A fix is referenced in commit bf1c76989e6a9054be4f0eb009d68f0f2464b453, indicating that a patch is available in the source code repository. Users of WWBN AVideo should update to a version including this commit or apply the fix manually. Since no official vendor advisory or patch release is provided, verify the fix status with the vendor or source repository. Until patched, consider implementing additional CAPTCHA validation controls or rate limiting on affected endpoints.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-04-15T20:40:15.518Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 69e7faaa19fe3cd2cd001491
Added to database: 4/21/2026, 10:31:06 PM
Last enriched: 4/21/2026, 10:46:55 PM
Last updated: 4/22/2026, 7:09:25 AM
Views: 13
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