FreeRDP before 3.29.0 TLS Certificate Identity Validation Bypass
FreeRDP · FreeRDP
Official source article: GitHub GHSA-43HH-P3VW-HFX3 ↗. Check the applicable product and release in the original source.
9.3CriticalCVSS 4.0
Recommended action
Patch only the product branches with a verified fix
Critical technical impact with a remotely reachable, unauthenticated path and a public exploit reference; no CISA KEV confirmation is currently recorded. Verified remediation exists for at least one product or source, but 169 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
Published severityCritical→Operational priority:Critical, unchanged from published severity.unchanged
Evidence used
No CISA KEV confirmation is currently recorded.
A structured source references public exploit or proof-of-concept material.
The selected CVSS metric records a network-reachable, unauthenticated path with no user interaction.
EPSS is 0.51% for the current model date.
Compensating controls
Validate the affected product branch and deploy the verified fixed release.
Restrict the affected network interface to trusted sources where business-safe.
Increase monitoring for the attack path and post-exploitation behaviour described in the report.
Verification
Confirm that the asset runs FreeRDP FreeRDP and falls inside the recorded affected range.
Verify the installed build against the product-specific fixed version after deployment.
Validate exposure, authentication requirements and compensating controls in the actual environment.
Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Cross-source reconciliation
Remediation availability differs by product scope
Verified remediation exists for at least one product or source, but 169 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
SUSE Product Security Team: 167 affected or under-investigation product states without a fixed product state in the same current advisory
Debian Security Tracker: 2 affected package states with no published fix
Distribution package intelligence
Release-specific package status
Debian, ubuntu findings are scoped to the named distribution, release and source package. An absent finding does not mean a package is unaffected.
6 package states
Package result overrides the generic status
BlackTree has verified remediation for at least one product or source, but the relevant distribution still reports no fixed package for 2 affected package states shown here. Treat those rows as affected with no fix until that distribution publishes a fixed version.
Repository candidate not checked
A published vendor fix does not prove that a matching update is enabled and installable on a particular asset. Confirm the local package candidate before scheduling remediation.
Distribution release
Source package
Vendor state
Fixed version
Evidence
Debian trixietrixie · source
freerdp3
Affected, no fix publishedDebian currently tracks this release as open.
Vendor fix publishedCanonical reports that a fixed source package version has been published. Repository candidate availability is not checked by BlackTree.
Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.
The vendor explicitly identifies these products as affected by this CVE.
freerdp as component of SUSE Linux Enterprise Desktop 15 SP7
freerdp-devel as component of SUSE Linux Enterprise Desktop 15 SP7
freerdp-proxy as component of SUSE Linux Enterprise Desktop 15 SP7
freerdp-proxy-plugins as component of SUSE Linux Enterprise Desktop 15 SP7
freerdp-sdl as component of SUSE Linux Enterprise Desktop 15 SP7
freerdp-server as component of SUSE Linux Enterprise Desktop 15 SP7
freerdp2 as component of SUSE Linux Enterprise Desktop 15 SP7
freerdp2-devel as component of SUSE Linux Enterprise Desktop 15 SP7
freerdp2-proxy as component of SUSE Linux Enterprise Desktop 15 SP7
freerdp2-server as component of SUSE Linux Enterprise Desktop 15 SP7
libfreerdp-server-proxy3-3 as component of SUSE Linux Enterprise Desktop 15 SP7
libfreerdp2-2 as component of SUSE Linux Enterprise Desktop 15 SP7
Summary
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.
Remediation
No remediation text is recorded.
Optional official sources
National CERT insights ?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.
Choose official national sources for this report. Each advisory shows its original language. Your selection is remembered on this device and included in shared links.
Official European source
ENISA European Vulnerability Database
Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.
1 current
ENISA EUVD identifier
EUVD-2026-51851
No EUVD known-exploited evidence
ENISA has published the identifier mapping but no EUVD description has been stored yet.
EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
Not supplied in the stored EUVD record
Advisory evidence
No linked advisory details stored yet
Recommended actionPatch only the product branches with a verified fix
Critical technical impact with a remotely reachable, unauthenticated path and a public exploit reference; no CISA KEV confirmation is currently recorded. Verified remediation exists for at least one product or source, but 169 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
Fix availability varies by product
01
What, why and how
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.
What
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.
Why
The product does not validate, or incorrectly validates, a certificate.
How
An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.
What
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.
Why
The product does not validate, or incorrectly validates, a certificate.
How
An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.
02
Exploit reality and attack path
CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.
Observed exploitation ?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No confirmed evidence
No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.
Public PoC / exploit material ?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.Reference recorded
A structured CVE source labels at least one public reference as exploit material. BlackTree has not independently validated that it is safe, reliable or weaponised.
Likely attack path
a network path → Improper Certificate Validation → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
User interaction
None
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Not a CVSS 4.0 base metric
Weakness ?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
Common Vulnerability Scoring System 4.0: the compact vector below is decoded into plain language.
AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.ATNoneAttack requirements: No additional deployment or execution condition is required.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.VCHighVulnerable-system confidentiality: A successful attack can cause a major loss.VIHighVulnerable-system integrity: A successful attack can cause a major loss.VAHighVulnerable-system availability: A successful attack can cause a major loss.SCNoneSubsequent-system confidentiality: No direct loss is represented by this metric.SINoneSubsequent-system integrity: No direct loss is represented by this metric.SANoneSubsequent-system availability: No direct loss is represented by this metric.
Post-exploitation / living off the land
No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
Ein Angreifer kann mehrere Schwachstellen in FreeRDP ausnutzen, um beliebigen Programmcode auszuführen, Sicherheitsmaßnahmen zu umgehen, vertrauliche Informationen offenzulegen, Daten zu manipulieren oder einen Denial-of-Service-Zustand auszulösen.
Official advisory ↗Cyber Security Agency of Singapore · English · CSA-SB-20260805Security Bulletin 5 Aug 2026
The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 5 Aug 2026, published on 5 August 2026. Open the linked bulletin for the product, severity and reference information published in that issue.
Official advisory ↗JVN iPedia · Japanese · JVNDB-2026-036477FreeRDPにおける証明書検証に関する脆弱性
FreeRDPは3.29.0より前のバージョン(影響を受けるのは3.28.0以前)において、tls_verify_certificate()、tls_match_hostname()、およびx509_utils_get_dns_names()に複数のTLS証明書アイデンティティ検証の弱点が含まれています。FreeRDPはOpenSSLの長さを考慮したアイデンティティ検証APIを使用せず、独自にCommon Name(CN)およびDNS SAN(DNSサブジェクト代替名)の文字列マッチングを行っているため、以下の問題が発生します。(1) 埋め込みNUL文字によりDNS SAN値が切り捨てられることがあり、例えば'victim.example\0.attacker.example'を'victim.example'として受け入れてしまいます。(2) DNS SANエントリが一致しなくても、共通名が一致すれば受け入れてしまいます。(3) IP Address SANを比較せずに、DNSおよびCNの照合だけでIPリテラルターゲットを受け入れてしまいます。信頼済みまたは不正に発行された証明書チェーンの下で、このような証明書を提示できる攻撃者はサーバーのアイデンティティ検証を回避し、TLSサーバー認証の安全性を低下させることが可能です。
Operational remediation based on structured source evidence.
Status ?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Use the product-specific evidence above. Patch only products with a verified fixed release, and keep every affected or under-investigation state without a matching fix in the remediation queue.
Workaround
A mitigation or workaround reference is available from the source linked below; validate it against the affected product and version.
04
Evidence and provenance
Published 1 Aug 2026 · Last source change 5 Aug 2026, 03:56 UTC · CWE-295 · Improper Certificate Validation
CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source ?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.FIRST · tracked since 2026-08-14
European sourceENISA EUVD · EUVD-2026-51851
Product sourceVendor CSAF · SUSE Product Security Team
Remediation sourceCVE/CNA references
CWE sourceCNA
NVD statusNVD enriched
Core structured fields are present and their contributing authorities are shown above.
Affected versionsThe structured affected or fixed version information changed.
Before
freerdp as component of SUSE Linux Enterprise Desktop 15 SP7; freerdp-devel as component of SUSE Linux Enterprise Desktop 15 SP7; freerdp-proxy as component of SUSE Linux Enterprise Desktop 15 SP7; freerdp-proxy-plugins as component of SUSE Linux Enterprise Desktop 15 SP7; freerdp-sdl as component of SUSE Linux Enterprise Desktop 15 SP7; freerdp-server as component of SUSE Linux Enterprise Desktop 15 SP7; freerdp2 as component of SUSE Linux Enterprise Desktop 15 SP7; freerdp2-devel as component of SUSE Linux Enterprise Desktop 15 SP7; freerdp2-proxy as component of SUSE Linux Enterprise Desktop 15 SP7; freerdp2-server as component of SUSE Linux Enterprise Desktop 15 SP7; libfreerdp-server-proxy3-3 as component of SUSE Linux Enterprise Desktop 15 SP7; libfreerdp2-2 as component of SUSE Linux Enterprise Desktop 15 SP7; libfreerdp3-3 as component of SUSE Linux Enterprise Desktop 15 SP7; librdtk0-0 as component of SUSE Linux Enterprise Desktop 15 SP7; libwinpr2-2 as component of SUSE Linux Enterprise Desktop 15 SP7; libwinpr3-3 as component of SUSE Linux Enterprise Desktop 15 SP7; winpr-devel as component of SUSE Linux Enterprise Desktop 15 SP7; winpr2-devel as component of SUSE Linux Enterprise Desktop 15 SP7; freerdp as component of SUSE Linux Enterprise High Performance Computing 12 SP5; freerdp-devel as component of SUSE Linux Enterprise High Performance Computing 12 SP5; freerdp-proxy as component of SUSE Linux Enterprise High Performance Computing 12 SP5; freerdp-server as component of SUSE Linux Enterprise High Performance Computing 12 SP5; libfreerdp2 as component of SUSE Linux Enterprise High Performance Computing 12 SP5; libwinpr2 as component of SUSE Linux Enterprise High Performance Computing 12 SP5; winpr2-devel as component of SUSE Linux Enterprise High Performance Computing 12 SP5; freerdp as component of SUSE Linux Enterprise Module for Package Hub 15 SP7; freerdp-devel as component of SUSE Linux Enterprise Module for Package Hub 15 SP7; freerdp-proxy as component of SUSE Linux Enterprise Module for Package Hub 15 SP7; freerdp-server as component of SUSE Linux Enterprise Module for Package Hub 15 SP7; freerdp-wayland as component of SUSE Linux Enterprise Module for Package Hub 15 SP7; and 115 more
After
freerdp as component of SUSE Linux Enterprise Desktop 15 SP7; freerdp-devel as component of SUSE Linux Enterprise Desktop 15 SP7; freerdp-proxy as component of SUSE Linux Enterprise Desktop 15 SP7; freerdp-proxy-plugins as component of SUSE Linux Enterprise Desktop 15 SP7; freerdp-sdl as component of SUSE Linux Enterprise Desktop 15 SP7; freerdp-server as component of SUSE Linux Enterprise Desktop 15 SP7; freerdp2 as component of SUSE Linux Enterprise Desktop 15 SP7; freerdp2-devel as component of SUSE Linux Enterprise Desktop 15 SP7; freerdp2-proxy as component of SUSE Linux Enterprise Desktop 15 SP7; freerdp2-server as component of SUSE Linux Enterprise Desktop 15 SP7; libfreerdp-server-proxy3-3 as component of SUSE Linux Enterprise Desktop 15 SP7; libfreerdp2-2 as component of SUSE Linux Enterprise Desktop 15 SP7; libfreerdp3-3 as component of SUSE Linux Enterprise Desktop 15 SP7; librdtk0-0 as component of SUSE Linux Enterprise Desktop 15 SP7; libwinpr2-2 as component of SUSE Linux Enterprise Desktop 15 SP7; libwinpr3-3 as component of SUSE Linux Enterprise Desktop 15 SP7; winpr-devel as component of SUSE Linux Enterprise Desktop 15 SP7; winpr2-devel as component of SUSE Linux Enterprise Desktop 15 SP7; freerdp as component of SUSE Linux Enterprise High Performance Computing 12 SP5; freerdp-devel as component of SUSE Linux Enterprise High Performance Computing 12 SP5; freerdp-proxy as component of SUSE Linux Enterprise High Performance Computing 12 SP5; freerdp-server as component of SUSE Linux Enterprise High Performance Computing 12 SP5; libfreerdp2 as component of SUSE Linux Enterprise High Performance Computing 12 SP5; libwinpr2 as component of SUSE Linux Enterprise High Performance Computing 12 SP5; winpr2-devel as component of SUSE Linux Enterprise High Performance Computing 12 SP5; freerdp as component of SUSE Linux Enterprise Module for Package Hub 15 SP7; freerdp-devel as component of SUSE Linux Enterprise Module for Package Hub 15 SP7; freerdp-proxy as component of SUSE Linux Enterprise Module for Package Hub 15 SP7; freerdp-server as component of SUSE Linux Enterprise Module for Package Hub 15 SP7; freerdp-wayland as component of SUSE Linux Enterprise Module for Package Hub 15 SP7; and 137 more
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.