CVE-2026-55191FreeRDP: Heap-buffer-overflow write in AVC444 YUV buffer allocation

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 HIGHEPSS 0.61%Not in KEVNVD: Analyzed

Last updated: 2026-10-26 11:10 UTC

OverviewCVSS details

8.7HIGHCVSS 4.0

Score source: GitHub_M (CNA)
NVD status: Analyzed
Published: Aug 19, 2026
Assigner: GitHub_M

Affected

FreeRDP (FreeRDP)

Versions: < 3.27.0

Exploitation

Public exploit: Yes · 1 reference
CISA KEV: Not listed
KEV due date: —
SSVC: Exploitation poc · Automatable no · Impact total

EPSS · FIRST, scored Nov 7

0.61%chance of exploitation in 30 days

Higher than 49.92% of CVEs

CVSS 4.0 · GitHub_M (CNA)

8.7High

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

Attack vector: Network
Attack complexity: Low
Attack requirements: None
Privileges required: None
User interaction: Passive
Confidentiality impact: High
Integrity impact: High
Availability impact: High
Confidentiality (other systems): None
Integrity (other systems): None
Availability (other systems): None

CVSS 3.1 · NVD

9.8Critical

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack vector: Network
Attack complexity: Low
Privileges required: None
User interaction: None
Scope: Unchanged
Confidentiality impact: High
Integrity impact: High
Availability impact: High

NVD status: Analyzed

Overview Affected Products References

NVD CVE.org

Overview

Severity

Score	Severity	Version	Vector String
8.7	HIGH	4.0GitHub_M (CNA)	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
9.8	CRITICAL	3.1NVD	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Details

CVE ID: CVE-2026-55191
Status: Analyzed
Assigner (CNA): GitHub_M
Published: Aug 19, 2026
Last modified: 2026-10-26 11:10 UTC
Weaknesses: CWE-122 · Heap-based Buffer Overflow
CWE-190 · Integer Overflow or Wraparound

Sources

Refreshed hourly from the sources above. Last fetched 2026-11-08 10:45 UTC.