CVE-2022-3924: isc bind Reachable Assertion

Vulnerability summary

CVE-2022-3924 is a high (CVSS 7.5) Reachable Assertion vulnerability in isc bind. EPSS estimates a 16.11% chance of exploitation in the next 30 days, higher than 96.8% of scored vulnerabilities.

Timeline

1. 25-01-2023
   PublishedVulnerability first disclosed.
2. 31-03-2025
   Last modifiedVulnerability information updated.

Description

This issue can affect BIND 9 resolvers with `stale-answer-enable yes;` that also make use of the option `stale-answer-client-timeout`, configured with a value greater than zero. If the resolver receives many queries that require recursion, there will be a corresponding increase in the number of clients that are waiting for recursion to complete. If there are sufficient clients already waiting when a new client query is received so that it is necessary to SERVFAIL the longest waiting client (see BIND 9 ARM `recursive-clients` limit and soft quota), then it is possible for a race to occur between providing a stale answer to this older client and sending an early timeout SERVFAIL, which may cause an assertion failure. This issue affects BIND 9 versions 9.16.12 through 9.16.36, 9.18.0 through 9.18.10, 9.19.0 through 9.19.8, and 9.16.12-S1 through 9.16.36-S1.

• CWE-617Reachable AssertionThe product contains an assert() or similar statement that can be triggered by an attacker, which leads to an application exit or other behavior that is more severe than necessary.