# CVE-2026-57163: PJSIP: Stack overflow parsing a TLS peer certificate's SubjectAltName in GnuTLS backend

> A stack buffer overflow in PJSIP's GnuTLS backend allows remote attackers to cause memory corruption or crashes via crafted TLS certificates.

- **Severity:** High 8.8 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 4 Sep 2026
- **Updated:** 4 Sep 2026
- **Also known as:** DEBIAN-CVE-2026-57163, GHSA-jm2j-6rg6-qvwx, UBUNTU-CVE-2026-57163

## What is CVE-2026-57163?

CVE-2026-57163 is a high-severity memory corruption vulnerability in pjsip pjproject, published on 4 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-121 (Stack-based Buffer Overflow)

## Which versions are affected by CVE-2026-57163?

It affects 1 product.


Products: Teluu Pjsip.

## How do I fix CVE-2026-57163?

No fix has been published for CVE-2026-57163 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-57163 being exploited?

There is no known exploitation of CVE-2026-57163 in the wild and no public exploit code.

## Other vulnerabilities in pjsip pjproject

- [CVE-2023-38703](https://insights.sbomify.com/CVE-2023-38703/): PJSIP has use-after-free vulnerability in SRTP media transport (critical 9.8)
- [CVE-2022-39269](https://insights.sbomify.com/CVE-2022-39269/): Media transport downgrade from the secure version (SRTP) to non-secure (RTP) in pjsip (critical 9.1)
- [CVE-2026-57161](https://insights.sbomify.com/CVE-2026-57161/): PJSIP: Stack overflow handling Service-Route headers in a registration response (high 8.8)
- [CVE-2026-57162](https://insights.sbomify.com/CVE-2026-57162/): PJSIP: Stack overflow parsing SDP a=crypto attributes (high 8.8)
- [CVE-2026-57159](https://insights.sbomify.com/CVE-2026-57159/): PJSIP: SDP parser out-of-bounds write in remote payload-type map maintenance (high 8.4)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-57163 and fix it if it is affected.

What it is: CVE-2026-57163 is a high-severity memory corruption vulnerability in pjsip pjproject, published on 4 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-57163 in the wild and no public exploit code.

Affected product: pjsip pjproject. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-57163/ (Markdown: https://insights.sbomify.com/CVE-2026-57163/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-57163
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-57163
- OSV: https://osv.dev/vulnerability/CVE-2026-57163

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-57163/
Summaries are generated and may contain mistakes; the official description above is the record.