CVE-2026-49953
Discuz! X5.0 CAPTCHA Bypass via Predictable Character Set
Published: Jun 15, 2026Updated: Jun 15, 2026 Sources: CVE List
6.5CVSS
MEDIUMDiscuz! X5.0 releases 20260320 through 20260501 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.
EPSS Score
N/A
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
No Fix Available
CVSS Vector Breakdown
Exploitability
AV:NAttack VectorNetwork
AC:LAttack ComplexityLow
PR:NPrivileges RequiredNone
UI:NUser InteractionNone
Scope
S:UScopeUnchanged
Impact
C:LConfidentialityLow
I:LIntegrityLow
A:NAvailabilityNone
Weaknesses
Affected Products
Discuz! X5.0
Discuz!
Exploitability
No known exploits, KEV entries, or remediation guidance available for this vulnerability yet.
References
Timeline
Published
Jun 15, 2026
Last Updated
Jun 15, 2026
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