SB2021021823 - Input validation error in Asterisk
Published: February 18, 2021 Updated: February 26, 2021
Security Bulletin ID
SB2021021823
Severity
Medium
Patch available
YES
Number of vulnerabilities
1
Exploitation vector
Remote access
Highest impact
Denial of service
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 1 security vulnerability.
1) Input validation error (CVE-ID: CVE-2021-26717)
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.
Remediation
Install update from vendor's website.
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