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Vulnerability record · CVE-2026-55191 · published 19 August 2026

CVE-2026-55191: Freerdp heap-based buffer overflow vulnerability

Freerdp · Freerdp

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.

8.7 CVSS 4.0 High EPSS 0.83% · top 44.2% CWE-122 · Heap-based buffer overflowCWE-190 · Integer overflow
8.7CVSS 4.0 base score
0.83%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
5References, 2 tagged exploit
22 Sep 2026Last modified by NVD

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.

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:

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/FreeRDP/FreeRDP/commit/97f40b9e766af375f4e41ac6a3f4397d708d249c Patch
https://github.com/FreeRDP/FreeRDP/pull/12873 Issue TrackingPatch
https://github.com/FreeRDP/FreeRDP/releases/tag/3.27.0 Release Notes
https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-vx73-w5q6-7jqr ExploitMitigationVendor Advisory
https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-vx73-w5q6-7jqr ExploitMitigationVendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-55191), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.