# CVE-2026-57161: PJSIP: Stack overflow handling Service-Route headers in a registration response

> A stack buffer overflow in PJSIP allows a malicious registrar to cause application termination via excessive Service-Route headers.

- **Severity:** High 8.8 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/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:** 9 Sep 2026
- **Also known as:** DEBIAN-CVE-2026-57161, GHSA-xc62-j9h2-mp84, UBUNTU-CVE-2026-57161

## What is CVE-2026-57161?

CVE-2026-57161 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 acc03b5, a stack buffer overflow exists in PJSUA when processing Service-Route headers in a registration response (update_service_route() in pjsua_acc.c). This affects applications that register using the PJSUA/PJSUA2 account API (the default registration path). The Service-Route URIs from a 2xx response to REGISTER are stored into a fixed-size array without bounding the number of headers; a registrar that returns an excessive number of Service-Route headers can write past the end of the array on the stack. The values written are internal pointers rather than arbitrary data, so the most likely impact is unexpected application termination (denial of service), though memory corruption cannot be excluded. The malicious response may come from a compromised or malicious registrar, or — over unprotected transports — a spoofed response. This issue has been patched via commit acc03b5.

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

## Which versions are affected by CVE-2026-57161?

It affects 1 product.


Products: Teluu Pjsip.

## How do I fix CVE-2026-57161?

No fix has been published for CVE-2026-57161 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-57161 being exploited?

There is no known exploitation of CVE-2026-57161 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-2026-57162](https://insights.sbomify.com/CVE-2026-57162/): PJSIP: Stack overflow parsing SDP a=crypto attributes (high 8.8)
- [CVE-2026-57163](https://insights.sbomify.com/CVE-2026-57163/): PJSIP: Stack overflow parsing a TLS peer certificate's SubjectAltName in GnuTLS backend (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-2026-57161 and fix it if it is affected.

What it is: CVE-2026-57161 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-2026-57161 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-2026-57161/ (Markdown: https://insights.sbomify.com/CVE-2026-57161/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-57161
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-57161
- OSV: https://osv.dev/vulnerability/CVE-2026-57161

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-57161/
Summaries are generated and may contain mistakes; the official description above is the record.