---
id: CVE-2026-57166
title: PJSIP is a free and open source multimedia communication library written in C
summary: >-
  PJSIP is a free and open source multimedia communication library written in C.
  Prior to commit 4472a31, a stack buffer overflow exists in the PJLIB-UTIL
  telnet CLI front-end when rendering feedback for an entered command line.
  Several co…
severity: medium
cvss: 5.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L'
cwe:
  - CWE-121
vendor: teluu
product: pjsip
affected:
  - pjsip <= 2.17
published: '2026-09-04'
updated: '2026-09-11'
sourceUpdated: '2026-09-11T16:53:31.460'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-57166'
references:
  - url: >-
      https://github.com/pjsip/pjproject/commit/4472a31d77a7506ff175dad5abef490f4e31bed1
    label: security-advisories@github.com
  - url: 'https://github.com/pjsip/pjproject/security/advisories/GHSA-9c8q-h38q-p85j'
    label: security-advisories@github.com
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-57166.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-57166'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-57166'
tags:
  - nvd
  - cve.org
  - csaf
  - vex
  - red-hat
  - score-dispute
epss: 0.00385
epssPercentile: 0.32317
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-09-09T16:03:10.770907Z'
scores:
  nvd: 5.3
  cna: 6.3
  vendor: 7.5
ingestedAt: '2026-09-08T22:12:30.947Z'
---

## Overview

PJSIP is a free and open source multimedia communication library written in C. Prior to commit 4472a31, a stack buffer overflow exists in the PJLIB-UTIL telnet CLI front-end when rendering feedback for an entered command line. Several command-line handling paths write an attacker-influenced amount of data into fixed-size buffers without sufficient bounds checking, so a long command line can overflow them. This affects only applications that enable the telnet CLI front-end (e.g. pj_cli_telnet_create() / --cli-telnet-port). The telnet CLI is an interactive administration interface with no authentication, so any client able to reach it can already issue arbitrary CLI commands. A malformed or overly long command line can overflow a fixed-size stack buffer while rendering command-line feedback, which may lead to application termination. Because reaching this code already requires access to the unauthenticated CLI, the impact beyond that existing access is limited. Applications that do not enable the telnet CLI front-end are not affected. This issue has been patched via commit 4472a31.

## Affected

- `pjsip <= 2.17`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Vendor advisories

- **Red Hat VEX** · updated 2026-09-09 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-57166.json)