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Fencer Intel
critical 9.8

CVE-2026-55191 json

FreeRDP: Heap-buffer-overflow write in AVC444 YUV buffer allocation

published 4mo ago modified 16d ago also EUVD-2026-62660 , GHSA-vx73-w5q6-7jqr

Unreviewed: the maintainers' own advisory

Published by the maintainers on their GitHub repository FreeRDP/FreeRDP. GitHub has not reviewed it into the GitHub Advisory Database, so the affected packages and versions are the maintainers' word. Read the full advisory on GitHub.

cvss
9.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 50%
public exploits
0
none known

Summary

FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to 3.27.0, FreeRDP clients that negotiate RDPGFX AVC444 with an H.264 decoder backend calculate the intermediate YUV444 allocation size in libfreerdp/codec/h264.c with 32-bit multiplication in avc444_ensure_buffer. A malicious RDP server can supply surface dimensions for which piDstStride multiplied by padDstHeight wraps to a small nonzero value, causing winpr_aligned_recalloc to allocate an undersized buffer before YUV420CombineToYUV444 writes using the actual stride and rectangle dimensions. This can cause a client crash and may permit code execution through attacker-influenced heap corruption. This issue is fixed in version 3.27.0.

Patch / fix

  • freerdp freerdp 3.27.0
  • freerdp3 Debian 14 3.27.0+dfsg-1

debian advisories DEBIAN-CVE-2026-55191

  • freerdp3 Ubuntu 24.04 LTS 3.30.0+dfsg-0ubuntu0.24.04.1
  • freerdp3 Ubuntu 26.04 LTS 3.30.0+dfsg-0ubuntu0.26.04.1

ubuntu advisories UBUNTU-CVE-2026-55191

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 openSUSE Tumbleweed 3.27.1-1.1

opensuse advisories openSUSE-SU-2026:11065-1

  • freerdp Alpine 3.24 3.27.1-r0

alpine advisories ALPINE-CVE-2026-55191

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Is CVE-2026-55191 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

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-2026-55191 updated cvss 8.8

FreeRDP: FreeRDP: Arbitrary code execution via heap-buffer-overflow in AVC444 YUV buffer allocation

  • Red Hat Enterprise Linux 6 freerdp, freerdp-libs, freerdp-plugins
    affected: workaround, no fix planned “Out of support scope”
  • 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 in execute path
  • Red Hat Enterprise Linux 10 freerdp
    not affected: component 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
Proof of concept is public
Automatable
no
Technical impact
total
Assessed
2mo ago

Exploit prediction

0.62% chance of exploitation in the next 30 days, higher than 50% of all scored CVEs (FIRST EPSS, 2026-11-11).

Exploits and checks

  • github.com https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-vx73-w5q6-7jqr referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 8.7 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
CNA 4.0 8.7 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/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
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

  • FreeRDP FreeRDP

Classification

Weakness
  • CWE-122 Heap-based Buffer Overflow
  • CWE-190 Integer Overflow or Wraparound

References

Sources

Fencer Intel 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.

The maintainers of FreeRDP/FreeRDP published their own advisory on GitHub. Reviewed sources take precedence over it.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.