CVE-2026-66402FreeRDP before 3.29.0 TLS Certificate Identity Validation Bypass
Updated under an hour ago ()
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It affects FreeRDP. Add what you run to find out whether that includes you.
No exploitation reported and no EPSS estimate yet.
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Free account, 1 product
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.
- CVSS
- 9.8 CRITICAL (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Weakness (CWE)
- CWE-295
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- VulnCheck
- NVD analysis
- Analyzed
- Record last updated
- Aug 5, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
FreeRDP FreeRDP freerdp:freerdp (from the name) | before 3.29.0; 3.29.0 not affected | CNA record |
freerdp freerdp freerdp:freerdp | before 3.29.0 | NVD |
References
- https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-43hh-p3vw-hfx3vendor-advisory, exploit, mitigation
- https://github.com/FreeRDP/FreeRDP/commit/b9533f07f98c25ed01c5f543b4d0ce73e120f5fdpatch
- https://www.vulncheck.com/advisories/freerdp-before-tls-certificate-identity-validation-bypassthird-party-advisory, patch
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.