CVE-2025-40777 – ” BIND Named CNAME Chain Abort Vulnerability”

CVE ID : CVE-2025-40777

Published : July 16, 2025, 6:15 p.m. | 20 minutes ago

Description : If a `named` caching resolver is configured with `serve-stale-enable` `yes`, and with `stale-answer-client-timeout` set to `0` (the only allowable value other than `disabled`), and if the resolver, in the process of resolving a query, encounters a CNAME chain involving a specific combination of cached or authoritative records, the daemon will abort with an assertion failure.
This issue affects BIND 9 versions 9.20.0 through 9.20.10, 9.21.0 through 9.21.9, and 9.20.9-S1 through 9.20.10-S1.

Severity: 7.5 | HIGH

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