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

Quick assessment

Affected
FreeRDP FreeRDP
Exploitation
Public or AI PoC available; prioritize validation
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

FreeRDP是FreeRDP组织开源的一款远程桌面协议(RDP)的实现。 FreeRDP 3.27.0之前版本存在安全漏洞，该漏洞源于在libfreerdp/codec/h264.c中avc444_ensure_buffer函数使用32位乘法计算缓冲区分配大小，导致整数溢出，可能造成堆损坏，攻击者可导致客户端崩溃并可能执行任意代码。

CVSS 8.7 · High EPSS 0.48% · P39

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 1

VendorProduct Version RangeStatus
FreeRDP FreeRDP < 3.27.0 affected
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I. Basic Information for CVE-2026-55191

Vulnerability Information
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Vulnerability Title
FreeRDP: Heap-buffer-overflow write in AVC444 YUV buffer allocation
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
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
Source: CVE Program / CVE List V5
Vulnerability Type
堆缓冲区溢出
Source: CVE Program / CVE List V5
Vulnerability Title
FreeRDP 缓冲区错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
FreeRDP是FreeRDP组织开源的一款远程桌面协议(RDP)的实现。 FreeRDP 3.27.0之前版本存在安全漏洞，该漏洞源于在libfreerdp/codec/h264.c中avc444_ensure_buffer函数使用32位乘法计算缓冲区分配大小，导致整数溢出，可能造成堆损坏，攻击者可导致客户端崩溃并可能执行任意代码。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
FreeRDP FreeRDP < 3.27.0 -

II. Public POCs for CVE-2026-55191

# POC Description Source Link Shenlong Link
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Qwen3.6-35B-A3B · 7382 chars
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Trigger conditions & impact
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III. Intelligence Information for CVE-2026-55191

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Patches & Fixes for CVE-2026-55191 (1)

Vendor Advisories for CVE-2026-55191 (1)

Vendor Pages for CVE-2026-55191 (1)

Same Patch Batch · FreeRDP · 2026-08-19 · 9 CVEs total

CVE-2026-55194 8.7 HIGH FreeRDPHeap-buffer-overflow write in TS Gateway RPC RESPONSE reassembly due to alloc_hint
CVE-2026-55193 8.7 HIGH FreeRDP: Heap-buffer-overflow write in TS Gateway RPC fragment receive due to uncapped bin
CVE-2026-63633 7.7 HIGH FreeRDP: Heap buffer overflow in Opus audio decode (`freerdp_dsp_decode_opus` resizes the
CVE-2026-55192 7.2 HIGH FreeRDP: Out-of-bounds read in H.264 YUV-to-RGB conversion due to decoder/surface dimensio
CVE-2026-63652 7.1 HIGH FreeRDP: Double-free of `client_formats` in the rdpsnd server channel on a malformed Clien
CVE-2026-63117 6.5 MEDIUM FreeRDP: Denial of service through ADPCM frame size calculation
CVE-2026-55648 6.1 MEDIUM FreeRDP: Integer Overflow in `freerdp_image_copy_from_icon_data` Bypasses Bounds Check
CVE-2026-55564 5.4 MEDIUM FreeRDP: Out-of-bounds read in glyph_cache_get via crafted glyph fragments

IV. Related Vulnerabilities

Same product: FreeRDP
Same vendor: FreeRDP
Same weakness: CWE-122

V. Comments for CVE-2026-55191

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