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CVE-2026-26965 high CVSS 8.8

Out-of-Bounds Write in FreeRDP (CVE-2026-26965)

Summary

Out-of-bounds write in FreeRDP (CVE-2026-26965). Successful exploitation can lead to full system takeover. Exploitable via pDstData.

Original description

The description as published by the source.

FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to version 3.23.0, in the RLE planar decode path, planar_decompress_plane_rle() writes into pDstData at ((nYDst+y) * nDstStep) + (4*nXDst) + nChannel without verifying that (nYDst+nSrcHeight) fits in the destination height or that (nXDst+nSrcWidth) fits in the destination stride. When TempFormat != DstFormat, pDstData becomes planar->pTempData (sized for the desktop), while nYDst is only validated against the surface by is_within_surface(). A malicious RDP server can exploit this to perform a heap out-of-bounds write with attacker-controlled offset and pixel data on any connecting FreeRDP client. The OOB write reaches up to 132,096 bytes past the temp buffer end, and on the brk heap (desktop ≤ 128×128), an adjacent NSC_CONTEXT struct's decode function pointer is overwritten with attacker-controlled pixel data — control-flow–relevant corruption (function pointer overwritten) demonstrated under deterministic heap layout (nsc->decode = 0xFF414141FF414141). Version 3.23.0 fixes the vulnerability.

Source: NIST National Vulnerability Database NVD GitHub Advisory

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2026-26965 has been found in FreeRDP.
Attackers can target a specific entry point like pDstData over the network to misuse the product.
Successful exploitation can lead to full system takeover. CVSS score: 8.8/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "FreeRDP CVE-2026-26965" on the vendor's site.

CVE-2026-26965 (FreeRDP) — CWE-787 / CVSS v3 8.8
Attack vector: remote (network-reachable) / unauthenticated
Attack surface: pDstData / nYDst / NSC_CONTEXT / decode
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

Out-of-bounds write (CWE-787) exists in FreeRDP. Attackers reach the vulnerable code path via pDstData without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of FreeRDP. Attack surface: pDstData / nYDst / NSC_CONTEXT / decode.

🔥 Severity

Severity: High (CVSS 8.8/10). Successful exploitation can lead to full system takeover.

🔧 How to fix

Update to the patched release per vendor advisory.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'FreeRDP' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

  1. 1
    Identify exposure identify 
    grep -r 'FreeRDP' . | grep -v node_modules

    リポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で FreeRDP を grep し、稼働しているサービス・バージョンを把握する。

  2. 2
    Post-deployment verification verify 
    Confirm patched version is live in production

    パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

Fix status by distribution

Fixed packages published by each distribution for this CVE

References

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