TLS authentication bypass via discarded GnuTLS trust status
Published May 7, 2026 · Updated May 7, 2026
Improper certificate validation in Teluu PJPROJECT before 2.17 allows attackers to bypass TLS peer authentication on GnuTLS builds. tls_cert_verify_cb previously mapped GnuTLS chain-trust failures into the SSL socket status only when verify_peer was true, leaving SIP TLS policy checks without the failure state. Client exploitation requires a network-positioned attacker and permits interception of outbound SIPS traffic; server exploitation accepts an otherwise untrusted client certificate.
Summary
What happened
Improper certificate validation in Teluu PJPROJECT before 2.17 allows attackers to bypass TLS peer authentication on GnuTLS builds. tls_cert_verify_cb previously mapped GnuTLS chain-trust failures into the SSL socket status only when verify_peer was true, leaving SIP TLS policy checks without the failure state. Client exploitation requires a network-positioned attacker and permits interception of outbound SIPS traffic; server exploitation accepts an otherwise untrusted client certificate.
The record
- CVE
- CVE-2026-42225
- Published
- May 7, 2026
- Updated
- May 7, 2026
- Vendor
- PJSIP
- Product
- PJPROJECT
- Classifications
- T1557
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- May 7, 2026CVE publishedPublication date reported by the CVE source.
- May 7, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
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- Affected versionversion=< 2.17
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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