CVE-2026-49953 Discuz! X5.0 CAPTCHA Bypass via Predictable Character Set
Attackers can bypass CAPTCHA protections in Discuz! X5.0 using OCR models, enabling automated abuse of login and registration features.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-49953?
CVE-2026-49953 is a medium-severity vulnerability in Discuz! X5.0, published on 15 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-804
Which versions are affected by CVE-2026-49953?
How do I fix CVE-2026-49953?
No fix has been published for CVE-2026-49953 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-49953 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-49953 exists.
Sources
Also known as GHSA-p3qj-vw7q-v9pc.