CVE-2026-57163
Received Received - Intake

Stack Buffer Overflow in PJSIP GnuTLS TLS Handshake

Publication date: 2026-09-04

Last updated on: 2026-09-04

Assigner: GitHub, Inc.

Description
PJSIP is a free and open source multimedia communication library written in C. Prior to commit c4a151a, a stack buffer overflow exists in the GnuTLS TLS backend when parsing the Subject Alternative Name extension of a peer certificate (tls_cert_get_info() in ssl_sock_gtls.c). Only GnuTLS builds are affected (--with-gnutls); OpenSSL and Apple SecureTransport/Network.framework builds are not affected. While extracting certificate information after a TLS handshake, an incorrect buffer-size value can cause an oversized SubjectAltName entry to be written past the end of a fixed-size stack buffer. A network-positioned attacker presenting a crafted certificate — a malicious server to a connecting client, or a malicious client to a server that requests certificates — can trigger this during the TLS handshake, before any SIP-level authentication. Impact may range from unexpected application termination to control flow hijack/memory corruption. This issue has been patched via commit c4a151a.

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Meta Information

Published
2026-09-04
Last Modified
2026-09-04
Generated
2026-09-05
AI Q&A
2026-09-04
EPSS Evaluated
N/A
NVD
CVE-2026-57163
EUVD
EUVD-2026-71657

Affected Vendors & Products

Showing 2 associated CPEs
Vendor Product Version / Range
pjproject pjsip to c4a151a (exc)
gnutls gnutls to c4a151a (exc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-121 A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).

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Executive Summary

This vulnerability is a stack buffer overflow in PJSIP, a multimedia communication library. It occurs in the GnuTLS TLS backend when parsing the Subject Alternative Name extension of a peer certificate. A fixed-size stack buffer is overwritten due to an incorrect buffer-size value, allowing a crafted certificate to trigger memory corruption or application termination during a TLS handshake.

Detection Guidance

To detect this vulnerability, check if your PJSIP version uses GnuTLS and is below the patched commit c4a151a. Inspect TLS handshake logs for crashes or memory corruption during certificate parsing. Use network monitoring tools to capture and analyze TLS certificates for oversized Subject Alternative Name entries.

Impact Analysis

An attacker could exploit this to cause unexpected application termination or take control of the application's memory, potentially leading to arbitrary code execution. This could compromise the confidentiality, integrity, or availability of the system running PJSIP.

Compliance Impact

This vulnerability could potentially impact compliance with GDPR and HIPAA by enabling unauthorized memory corruption or control flow hijacking during TLS handshakes. If exploited, it may lead to data breaches or unauthorized access to sensitive information, which are key concerns under these regulations.

Mitigation Strategies

Update PJSIP to a version that includes commit c4a151a or later. If using GnuTLS builds, ensure the library is updated to address the stack buffer overflow in Subject Alternative Name parsing.

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