Input validation error in Asterisk Open Source - CVE-2021-26717
Published: February 18, 2021 / Updated: February 26, 2021
Vulnerability identifier: #VU50966
CSH Severity: Medium
CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2021-26717
CWE-ID: CWE-20
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote non-authenticated attacker to perform a denial of service (DoS) attack.
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.
Affected software
Asterisk Open Source
asterisk (Alpine package)
asterisk (Alpine package)
How to mitigate CVE-2021-26717
Install update from vendor's website.
asterisk (Alpine package) - update to 16.16.1-r0
External References
- http://packetstormsecurity.com/files/161471/Asterisk-Project-Security-Advisory-AST-2021-002.html
- http://seclists.org/fulldisclosure/2021/Feb/58
- https://downloads.asterisk.org/pub/security/
- https://downloads.asterisk.org/pub/security/AST-2021-002.html
- https://issues.asterisk.org/jira/browse/ASTERISK-29203