CVE-2021-26717

Publication date 18 February 2021

Last updated 11 July 2025

Ubuntu priority

Cvss 3 Severity Score

Description

An issue was discovered in Sangoma Asterisk 16.x before 16.16.1, 17.x before 17.9.2, and 18.x before 18.2.1 and Certified Asterisk before 16.8-cert6. When re-negotiating for T.38, if the initial remote response was delayed just enough, Asterisk would send both audio and T.38 in the SDP. If this happened, and the remote responded with a declined T.38 stream, then Asterisk would crash.

Read the notes from the security team

Status

Show unmaintained releases

Package	Ubuntu Release	Status
asterisk	25.10 questing	Vulnerable
	25.04 plucky	Vulnerable
	24.10 oracular	Ignored end of life, was needed
	24.04 LTS noble	Vulnerable
	23.10 mantic	Ignored end of life, was needed
	23.04 lunar	Ignored end of life, was needed
	22.10 kinetic	Ignored end of life, was needed
	22.04 LTS jammy	Vulnerable
	21.10 impish	Ignored end of life
	21.04 hirsute	Ignored end of life
	20.10 groovy	Not affected
	20.04 LTS focal	Not affected
	18.04 LTS bionic	Not affected
	16.04 LTS xenial	Not affected
	14.04 LTS trusty	Not in release

Notes

sbeattie

introduced in 16.15.0 upstream

Severity score breakdown

Parameter	Value
Base score	7.5 · High
Attack vector	Network
Attack complexity	Low
Privileges required	None
User interaction	None
Scope	Unchanged
Confidentiality	None
Integrity impact	None
Availability impact	High
Vector	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H