CVE-2022-3924: ISC BIND

High severity, CVSS 7.5. EPSS: 16.1% chance of exploitation in the next 30 days.

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.

Affected products

• ISC BIND: from 9.16.12, before 9.16.37 (fixed in 9.16.37); from 9.18.0, before 9.18.11 (fixed in 9.18.11); from 9.19.0, before 9.19.9 (fixed in 9.19.9); version 9.16.12 only; version 9.16.13 only; version 9.16.14 only; …

Published 2023-01-26. Last modified 2026-06-17.