CVE-2026-91949
CRITICALDescription
FreeRDP server versions before 3.31.0 contain a protocol negotiation bypass vulnerability that allows unauthenticated attackers to establish RDSTLS connections despite server policy disabling them. Attackers can send incompatible protocol requests, receive negotiation failures, then complete TLS handshake and enter RDSTLS to bypass pre-authentication transport restrictions.
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:C/C:H/I:L/A:N
Exploit Intelligence
EPSS data unavailable for this CVE.
References
Related Vulnerabilities
Other CWE-693 (Protection Mechanism Failure) vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2013-2465 | Critical | 9.8 | 99% | KEV + Ransom | - |
| CVE-2019-1003030 | Critical | 9.9 | 97% | KEV | - |
| CVE-2024-21412 | High | 8.1 | 95% | KEV + Ransom | Fix |
| CVE-2013-0431 | Medium | 5.3 | 90% | KEV + Ransom | - |
| CVE-2025-40536 | High | 8.1 | 82% | KEV | Fix |
| CVE-2025-0411 | High | 7.0 | 67% | KEV | Fix |
Common questions
How do I fix CVE-2026-91949?
No published fix for CVE-2026-91949 has been found yet. Check the linked vendor advisories for guidance as it becomes available.
How severe is CVE-2026-91949?
CVE-2026-91949 has a CVSS v3 base score of 9.3, rated critical. 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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Markdown
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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 2026-09-17.