CVE-2026-49953
Discuz! X5.0 CAPTCHA Bypass via Predictable Character Set
CVSS Score
6.5
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-804 |
| Vendor | discuz! |
| Product | discuz! x5.0 |
| Published | Jun 15, 2026 |
| Last Updated | Jun 15, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
None
Affected Versions
Discuz! / Discuz! X5.0
20260320 ≤ 20260610
References
Credits
Egidio Romano