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.
References10
- github.com/asterisk/asterisk/commit/02e2d8d51efe1f811f292922433…
- github.com/asterisk/asterisk/commit/4f5cad0611c67638a0a61cfedbe…
- github.com/asterisk/asterisk/commit/9b085d48fb66e90a0740ea59e26…
- github.com/asterisk/asterisk/commit/a0bc717b2261f4df7cdecc22b58…
- github.com/asterisk/asterisk/commit/a2f1cc611f7d0f21faa03e85350…
- github.com/asterisk/asterisk/commit/aa40bc599a8e628859ef1c4fc94…
- github.com/asterisk/asterisk/commit/d4ccfd55ffd7cf6d73a6e5cde34…
- github.com/asterisk/asterisk/releases/tag/20.20.1
- github.com/asterisk/asterisk/releases/tag/21.12.3
- github.com/asterisk/asterisk/releases/tag/22.10.1
Metrics
- CVSS 4.0
-
6.0
MEDIUM
Score source: CNA
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - EPSS — exploit probability
- 1% percentile: 51 · as of 3 November 2026
- CWE
- CWE-125CWE-131CWE-787
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.