CVE-2026-49953
MEDIUMDescription
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.
How to fix
No published remediation has been found for this vulnerability's affected products yet.
Mitigation guidance may be in the linked vendor advisories in the References section below.
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CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Exploit Intelligence
Low risk: more likely to be exploited than 29% of all known CVEs.
References
Related Vulnerabilities
Other CWE-804 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2022-1801 | High | 7.5 | 1.2% | - | Fix |
| CVE-2023-6963 | Medium | 5.3 | 0.5% | - | Fix |
| CVE-2024-30540 | Medium | 5.3 | 0.5% | - | - |
| CVE-2025-8546 | Medium | 5.3 | 0.5% | - | - |
| CVE-2022-4036 | Medium | 5.3 | 0.4% | - | - |
| CVE-2025-10423 | Low | 3.7 | 0.4% | - | - |
Common questions
How do I fix CVE-2026-49953?
No published fix for CVE-2026-49953 has been found yet. Check the linked vendor advisories for guidance as it becomes available.
Is CVE-2026-49953 being actively exploited?
Not that we know of. CVE-2026-49953 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.36% is the estimated probability that it will be exploited in the next 30 days. That is higher than 29% of all scored CVEs.
How severe is CVE-2026-49953?
CVE-2026-49953 has a CVSS v3 base score of 6.5, rated medium. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-06-16.