CVE-2026-55191

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.

• CWE-122
• CWE-190

• https://github.com/FreeRDP/FreeRDP/commit/97f40b9e766af375f4e41ac6a3f4397d708d249cPatch
• https://github.com/FreeRDP/FreeRDP/pull/12873Issue Tracking, Patch
• https://github.com/FreeRDP/FreeRDP/releases/tag/3.27.0Release Notes
• https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-vx73-w5q6-7jqrExploit, Mitigation, Vendor Advisory
• https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-vx73-w5q6-7jqrExploit, Mitigation, Vendor Advisory

Published

Aug 19, 2026

Last Modified

Sep 22, 2026

Status

Analyzed

• How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
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