CVE-2026-49953
Discuz! X5.0 CAPTCHA Bypass via Predictable Character Set
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.
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
Affected products
Discuz! · Discuz! X5.0public PoCs found — 1
cve_referencekarmainsecurity.com/chaining-bugs-in-discuz-from-race-condition-to-rceunverified⚠ Public resources, to assess the exposure of systems you control or are authorized to test. Test only with authorization.
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