---
id: "CVE-2026-57192"
kind: "vulnerability"
aliases: ["CVE-2026-57192"]
title: "Asterisk: Codec2 decoder heap overflow lets authenticated SIP callers corrupt memory"
severity: "medium"
cvss: 6.0
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["asterisk", "pbx", "runtime", "sip", "voip"]
not_affected_if: ["codec2-not-enabled", "codec2-not-loaded", "fixed-version"]
published_at: "2026-10-27T22:17:27+00:00"
first_seen_at: "2026-10-27T22:29:29+00:00"
updated_at: "2026-10-27T22:30:17+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-57192", "first_seen_at": "2026-10-27T22:29:29+00:00"}]
---

# Asterisk: Codec2 decoder heap overflow lets authenticated SIP callers corrupt memory

Asterisk's Codec2 audio decoder writes past a heap buffer when a call sends crafted Codec2 packets, because the floor and ceil sample counts do not match. An authenticated SIP caller can use this to corrupt memory in the PBX process.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Run `asterisk -rx "core show version"` and compare against the fixed releases.
- Check whether the `codec_codec2` module is loaded with `asterisk -rx "module show like codec2"`.
- Check whether Codec2 is enabled in SIP peer or endpoint configuration, for example `grep -i codec2 /etc/asterisk/*.conf`.

## Fix

- Upgrade Asterisk to `20.20.1`, `21.12.3`, `22.10.1` or `23.4.1`, or Certified Asterisk to `20.7-cert11` or `22.8-cert3`.
- Until upgraded, unload `codec_codec2` or remove Codec2 from endpoint codec lists.

## Timeline

- 2026-10-27T22:29:29+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-57192

## From the sources

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.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_