Description
Discuz! X5.0 releases 20260320 through 20260610 contains a CAPTCHA bypass vulnerability that allows unauthenticated remote attackers to defeat challenge controls by exploiting limited complexity and predictable character sets in generated CAPTCHA images. Attackers can train a custom optical character recognition model against collected CAPTCHA samples to reliably predict challenge text, bypassing protections on login, registration, and other functionality from automated abuse.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Discuz! | Discuz! X5.0 | 20260320 – ≤ 20260610 | — |
References
- https://karmainsecurity.com/KIS-2026-10 technical-description
- https://karmainsecurity.com/chaining-bugs-in-discuz-from-race-condition-to-rce exploit
- https://www.vulncheck.com/advisories/discuz-x5-0-captcha-bypass-via-predictable-character-set third-party-advisory