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Fencer Vulns
critical 9.3

CVE-2026-91949 json

FreeRDP 3.0.0 through 3.30.0 Protocol Negotiation Bypass

published 2026-09-15 55 d ago modified 2026-09-24 46 d ago also EUVD-2026-78806

cvss
9.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 47%
public exploits
0
none known

Summary

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.

Patch / fix

  • FreeRDP FreeRDP 3.31.0
  • freerdp3 Debian 14 3.31.0+dfsg-1

debian advisories DEBIAN-CVE-2026-91949

  • freerdp3 Ubuntu 24.04 LTS 3.31.0+dfsg-0ubuntu0.24.04.1
  • freerdp3 Ubuntu 26.04 LTS 3.31.0+dfsg-0ubuntu0.26.04.1

ubuntu advisories UBUNTU-CVE-2026-91949

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • freerdp RHEL 10.2 2:3.10.3-12.el10_2.13
  • libwinpr RHEL 10.2 2:3.10.3-12.el10_2.13
  • freerdp-libs RHEL 10.2 2:3.10.3-12.el10_2.13
  • freerdp-server RHEL 10.2 2:3.10.3-12.el10_2.13
  • freerdp enterprise linux eus 10.0 2:3.10.3-3.el10_0.18
  • libwinpr enterprise linux eus 10.0 2:3.10.3-3.el10_0.18
  • freerdp-libs enterprise linux eus 10.0 2:3.10.3-3.el10_0.18
  • freerdp-server enterprise linux eus 10.0 2:3.10.3-3.el10_0.18

red hat advisories RHSA-2026:73979RHSA-2026:74471

  • freerdp AlmaLinux 10 2:3.10.3-12.el10_2.13
  • libwinpr AlmaLinux 10 2:3.10.3-12.el10_2.13
  • freerdp-libs AlmaLinux 10 2:3.10.3-12.el10_2.13
  • freerdp-server AlmaLinux 10 2:3.10.3-12.el10_2.13

almalinux advisories ALSA-2026:73979

  • freerdp Rocky Linux 10 2:3.10.3-12.el10_2.13

rocky linux advisories RLSA-2026:73979

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-91949 updated cvss 9.3

freerdp: FreeRDP 3.0.0 through 3.30.0 Protocol Negotiation Bypass

  • Red Hat Enterprise Linux AppStream (v. 10) freerdp 3.10.3-12.el10_2.13, libwinpr 3.10.3-12.el10_2.13, freerdp-libs 3.10.3-12.el10_2.13
    fixed: vendor fix RHSA-2026:73979
  • Red Hat Enterprise Linux AppStream EUS (v. 10.0) freerdp 3.10.3-3.el10_0.18, libwinpr 3.10.3-3.el10_0.18, freerdp-libs 3.10.3-3.el10_0.18
    fixed: vendor fix RHSA-2026:74471
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) freerdp-server 3.10.3-12.el10_2.13
    fixed: vendor fix RHSA-2026:73979
  • Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0) freerdp-server 3.10.3-3.el10_0.18
    fixed: vendor fix RHSA-2026:74471
  • Red Hat Enterprise Linux 6 freerdp, freerdp-libs, freerdp-plugins Red Hat Enterprise Linux 7 freerdp, libwinpr, freerdp-libs, freerdp-plugins Red Hat Enterprise Linux 8 freerdp, libwinpr, freerdp-libs Red Hat Enterprise Linux 9 freerdp, libwinpr, freerdp-libs
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
52 d ago

Exploit prediction

0.58% chance of exploitation in the next 30 days, higher than 47% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-x7v6-xfx3-52j6 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 9.2 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:L/VA:N/SC:H/SI:L/SA:N
CNA 3.1 9.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N
CNA 4.0 9.2 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:L/VA:N/SC:H/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Affected products

  • FreeRDP FreeRDP

Classification

Weakness
  • CWE-693 Protection Mechanism Failure

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.