CVE-2026-49953

Name of the Vulnerable Software and Affected Versions Discuz! X5.0 versions 20260320 through 20260610

Description A CAPTCHA bypass 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 (OCR) model—a technology that converts images of text into machine-encoded text—against collected samples to reliably predict challenge text, bypassing protections on login, registration, and other functionality from automated abuse.

Recommendations Update to a version later than 20260610.