Discover the details of CVE-2021-26717, a vulnerability in Sangoma Asterisk versions 16.x, 17.x, and 18.x before specified versions, leading to crashes during T.38 renegotiation.
A vulnerability has been discovered in Sangoma Asterisk versions 16.x, 17.x, and 18.x, as well as Certified Asterisk before 16.8-cert6. This vulnerability could lead to a crash under specific conditions during T.38 renegotiation.
Understanding CVE-2021-26717
This section will cover the details of the CVE-2021-26717 vulnerability.
What is CVE-2021-26717?
The vulnerability in Sangoma Asterisk versions could result in a crash due to a specific scenario during T.38 renegotiation.
The Impact of CVE-2021-26717
If exploited, this vulnerability could cause Asterisk to crash, affecting the availability of the service and potentially leading to denial of service (DoS) attacks.
Technical Details of CVE-2021-26717
This section will delve into the technical aspects of the CVE-2021-26717 vulnerability.
Vulnerability Description
When re-negotiating for T.38, if Asterisk sends both audio and T.38 in the Session Description Protocol (SDP) and the remote responds with a declined T.38 stream, Asterisk crashes.
Affected Systems and Versions
Sangoma Asterisk versions 16.x, 17.x, and 18.x, as well as Certified Asterisk before 16.8-cert6, are affected by this vulnerability.
Exploitation Mechanism
The vulnerability is triggered when the initial remote response is delayed just enough during T.38 renegotiation, leading to the crash in Asterisk.
Mitigation and Prevention
This section will provide guidance on mitigating the CVE-2021-26717 vulnerability.
Immediate Steps to Take
Users are advised to update to Sangoma Asterisk versions 16.16.1, 17.9.2, 18.2.1, or Certified Asterisk 16.8-cert6 to mitigate this vulnerability.
Long-Term Security Practices
It is recommended to keep systems up to date with the latest security patches and follow secure configuration practices to reduce the risk of exploitation.
Patching and Updates
Regularly checking for updates and applying patches from Sangoma to address security vulnerabilities is crucial in maintaining a secure environment.