Vulnerability in freerdp (UBUNTU-CVE-2026-66402)

Summary

Vulnerability in freerdp (UBUNTU-CVE-2026-66402). Successful exploitation can lead to full system takeover. Mitigation: upgrade to 3.30.0+dfsg-0ubuntu0.24.04.1 or later.

Original description

The description as published by the source.

FreeRDP before 3.29.0 (affected versions <= 3.28.0) contains multiple TLS certificate identity validation weaknesses in tls_verify_certificate(), tls_match_hostname(), and x509_utils_get_dns_names(). Because FreeRDP performs custom Common Name and DNS SAN string matching instead of using OpenSSL's length-aware identity validation APIs, it (1) truncates DNS SAN values at embedded NUL bytes (accepting e.g. 'victim.example\0.attacker.example' as 'victim.example'), (2) accepts a matching Common Name even when non-matching DNS SAN entries are present, and (3) accepts IP-literal targets via DNS/CN matching without comparing iPAddress SANs. Under a trusted or misissued certificate chain, an attacker positioned to present such a certificate can bypass server identity verification, weakening TLS server authentication.

Source: OSV.dev (Open Source Vulnerabilities) OSV

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 UBUNTU-CVE-2026-66402 has been found in freerdp.
Successful exploitation can lead to full system takeover.
What to do: upgrade freerdp to 3.30.0+dfsg-0ubuntu0.24.04.1 or later.
If unsure, ask your IT team or search "freerdp UBUNTU-CVE-2026-66402" on the vendor's site.

UBUNTU-CVE-2026-66402 (freerdp)
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Patched: 3.30.0+dfsg-0ubuntu0.24.04.1 — apply immediately
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

A vulnerability (unclassified) exists in freerdp.

📍 Affected scope

Check the vendor advisory for the affected versions of freerdp.

🔥 Severity

Severity: ?. Successful exploitation can lead to full system takeover.

🔧 How to fix

Update to 3.30.0+dfsg-0ubuntu0.24.04.1.

🛡️ 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
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
Apply patch patch
```
Upgrade freerdp to 3.30.0+dfsg-0ubuntu0.24.04.1
```
ステージング環境で 3.30.0+dfsg-0ubuntu0.24.04.1 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
3
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。