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CVE-2026-55191

Status: AnalyzedHigh (8.7)—

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

Exploitation probability (EPSS)

EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).

🎯 ATT&CK techniques

How this vulnerability is exploited and what the attacker gains, in MITRE ATT&CK terms.

Vector CVSS con UI:R indica interacción del usuario (conectarse a servidor RDP malicioso). Servidor RDP malicioso causa corrupción de heap y crash del cliente, permitiendo ejecución de código (T1059) o DoS (T1499.004).

Inferred by our analysis agent from the official description, CVSS vector and CWE, and checked by a supervisor. May contain errors.

🛡️ ATT&CK mitigations that cover these techniques

Restrict Web-Based ContentPrivileged Account ManagementLimit Software InstallationFilter Network TrafficExecution PreventionBehavior Prevention on Endpoint

Affected technologies (1)

Freerdp — Freerdp

CWEs

References

Raw JSON (NVD)

Show
{
  "id": "CVE-2026-55191",
  "cveTags": [],
  "metrics": {
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          "options": [
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          "modifiedAttackRequirements": "NOT_DEFINED",
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          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
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      "source": "security-advisories@github.com"
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    {
      "url": "https://github.com/FreeRDP/FreeRDP/releases/tag/3.27.0",
      "tags": [
        "Release Notes"
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      "source": "security-advisories@github.com"
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      "source": "security-advisories@github.com",
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          "value": "CWE-122"
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          "lang": "en",
          "value": "CWE-190"
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      "value": "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."
    }
  ],
  "lastModified": "2026-09-22T19:47:02.713",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
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              "criteria": "cpe:2.3:a:freerdp:freerdp:*:*:*:*:*:*:*:*",
              "vulnerable": true,
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              "versionEndExcluding": "3.27.0"
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