What is CVE-2026-91949?

CVE-2026-91949 is a critical-severity vulnerability in Freerdp, classified under Protection Mechanism Failure. CVSS score: 9.3/10. Published 2026-09-15.

How severe is CVE-2026-91949?

Critical severity. CVSS v3 base score is 9.3 out of 10.

Vulnerability in Freerdp

CVE-2026-91949

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.

CVSS v3 metric

CVSS v3 base score 9.3 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N.

Affected products

Freerdp

Weakness classification (CWE)

CWE-693 — Protection Mechanism Failure

References

disclosure@vulncheck.com (vendor-advisory)
disclosure@vulncheck.com (third-party-advisory)

Frequently asked questions

What is CVE-2026-91949?: CVE-2026-91949 is a critical-severity vulnerability in Freerdp, classified under Protection Mechanism Failure. CVSS score: 9.3/10. Published 2026-09-15.
How severe is CVE-2026-91949?: Critical severity. CVSS v3 base score is 9.3 out of 10.