CVE-2021-25215 : What You Need to Know
Learn about CVE-2021-25215 affecting BIND 9 versions, causing assertion check failures when processing certain records, leading to denial-of-service vulnerabilities. Upgrade to patched releases for protection.
In BIND 9.0.0 -> 9.11.29, 9.12.0 -> 9.16.13, and versions BIND 9.9.3-S1 -> 9.11.29-S1 and 9.16.8-S1 -> 9.16.13-S1 of BIND Supported Preview Edition, as well as release versions 9.17.0 -> 9.17.11 of the BIND 9.17 development branch, when a vulnerable version of named receives a query for a record triggering the flaw described above, the named process will terminate due to a failed assertion check. The vulnerability affects all currently maintained BIND 9 branches (9.11, 9.11-S, 9.16, 9.16-S, 9.17) as well as all other versions of BIND.
Understanding CVE-2021-25215
This CVE impacts BIND 9 versions and can lead to a denial-of-service condition due to failed assertion checks.
What is CVE-2021-25215?
It is a vulnerability in BIND that causes the named process to terminate when processing queries for certain records, triggering a failed assertion check.
The Impact of CVE-2021-25215
The vulnerability can be exploited by an attacker to cause denial of service in the affected BIND servers.
Technical Details of CVE-2021-25215
The vulnerability arises from the processing of DNAME records in the DNS, potentially leading to failed assertion checks.
Vulnerability Description
DNAME records, used to redirect parts of the domain tree, may trigger multiple RRset additions, causing BIND to fail assertion checks.
Affected Systems and Versions
Versions affected include various branches of BIND 9, such as Open Source Branches 9.0 through 9.11 and Supported Preview Branches 9.9-S through 9.11-S.
Exploitation Mechanism
The vulnerability is triggered when a vulnerable named server receives a specific query, resulting in termination due to assertion failures.
Mitigation and Prevention
Upgrading to patched releases is the recommended solution.
Immediate Steps to Take
Upgrade to the closest patched version: BIND 9.11.31, BIND 9.16.15, or BIND 9.17.12.
Long-Term Security Practices
Regularly update BIND installations and follow security advisories to stay protected.
Patching and Updates
Install updates promptly to address vulnerabilities and secure your BIND deployments.