CVE-2025-40777
7.5
HIGH
CVSS 3.1
EPSS 0.10%
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.
How to fix CVE-2025-40777
To remediate CVE-2025-40777, upgrade the affected package to a fixed version below.
- —upgrade to 9.20.11-r0 or later
- —no fix listed
Is CVE-2025-40777 being exploited?
Low — EPSS is 0.1%, meaning exploitation activity has not been observed at scale.
Affected packages (2)
- from 0, < 9.20.11-r0
- from 0
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | HIGH7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |