CVE-2025-40777 — A possible assertion failure when 'stale-answer-client-timeout' is set to '0'
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`), …
Published: 2025-07-16 · CVSS: 7.5 · CVSS 3.1
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.
Source: CVE Program · Revision 8b16575c39f1e1810c5e863010da073d2d3285e7