Reference page — cumulative record through Saturday, October 3, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.

CVE-2026-55191

CVE-2026-55191HIGH

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

  AV  AC  AT  PR  UI  VC  VI  VA   CVSS    EPSS   %ile   KEV
   N   L   N   N   P   H   H   H    8.7   .0083   56.0     —

AFFECTED
  Product  Versions    Fixed
  FreeRDP  < 3.27.0 –  —

TIMELINE
  Jun 16  Reserved by GitHub_M
  Aug 19  Published (CNA: GitHub_M)
  Sep 22  EXPLOIT PUBLISHED — CVE-2026-55191 (FreeRDP). Public exploit reference added.

CWE-122, CWE-190 · CNA: GitHub_M · CVSS v4.0 · 4 references · NVD status: Analyzed

Description

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.

Lifecycle

Complete event history — 3 events, chronological
Date	Event	Detail
June 16, 2026	Reserved	Reserved by GitHub_M
August 19, 2026	Published	Published (CNA: GitHub_M)
September 22, 2026	EXPLOIT PUBLISHED	EXPLOIT PUBLISHED — CVE-2026-55191 (FreeRDP). Public exploit reference added.

Affected

Affected products and packages — 1 row
Vendor	Product / Package	Ecosystem	Version introduced	Fixed
FreeRDP	FreeRDP	—	< 3.27.0	—

Weaknesses

CWE-122 · CWE-190

References (4)

https://github.com/FreeRDP/FreeRDP/commit/97f40b9e766af375f4e41ac6a3f4397d708d249c [Patch]
https://github.com/FreeRDP/FreeRDP/pull/12873 [Issue Tracking, Patch]
https://github.com/FreeRDP/FreeRDP/releases/tag/3.27.0 [Release Notes]
https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-vx73-w5q6-7jqr [Exploit, Mitigation, Vendor Advisory]

Authoritative record: CVE-2026-55191 at cve.org

Vendors: freerdp

Weaknesses: CWE-122 · CWE-190

About this page

This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2026-55191 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Saturday, October 3, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.