CVEvulnerability
CVE-2026-49953
6.9 MEDIUM
Official page ↗
- Status
- Deferred
- Published
- 2026-06-15
- Last modified
- 2026-10-25
- Assigner
- [email protected]
- CVSS 4.0 ([email protected])
- 6.9 MEDIUM — CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
- CVSS 3.1 ([email protected])
- 6.5 MEDIUM — CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
- Weaknesses
- CWE-804
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.
Related
Weakness · CWE (1)
- CWE-804 Guessable CAPTCHA weakness
References
- https://karmainsecurity.com/KIS-2026-10 karmainsecurity.com
- https://karmainsecurity.com/chaining-bugs-in-discuz-from-race-condition-to-rce karmainsecurity.com
- https://www.vulncheck.com/advisories/discuz-x5-0-captcha-bypass-via-predictable-character-set www.vulncheck.com
- http://seclists.org/fulldisclosure/2026/Jun/4 seclists.org