Machine-written summary
Summary written by Claude Haiku from the source advisory. Not reviewed by a person.
Zend-Captcha versions from 2.0.0 before 2.4.9 and from 2.5.0 before 2.5.2 are affected. The Word CAPTCHA generator picks its characters with PHP's array_rand(), which relies on weak randomness, so an attacker who can brute-force that random number generation could recover CAPTCHA words. The source gives few details about the exact attack conditions. Upgrade to zend-captcha 2.4.9 or 2.5.2.
Not analysed yet
We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.
Severity and exploitation
| Score | Rating | CVSS | Vector | Source |
|---|---|---|---|---|
| 7.5 | High | 3.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N | GitHub Advisory Database |
- CISA KEV Not listed.
- EPSS No score.
Timeline
- 31 Oct 2026, 14:28 UTC First seen by agentprime
- 31 Oct 2026, 14:28 UTC Confirmed by OSV
Sources
- GitHub Advisory Database: GHSA-mg4x-prh7-g4mx
- OSV: GHSA-mg4x-prh7-g4mx
- github.com/zendframework/zend-captcha/commit/43c276df6e94e498bf530538aea53876a24fc47c
- github.com/zendframework/zend-captcha/commit/5561ef813bb4ad814e835343289dc5077d2eb262
- framework.zend.com/security/advisory/ZF2015-09
- github.com/FriendsOfPHP/security-advisories/blob/master/zendframework/zend-captcha/ZF2015-09.yaml
- github.com/zendframework/zend-captcha