CVE-2025-40777
A possible assertion failure when 'stale-answer-client-timeout' is set to '0'
HIGH 7.5
At a glance
- Source
- NVD
- EPSS
- EPSS 1.02 % · percentile 63 ()
- State
- PUBLISHED
- Published
- Updated
- Assigner
- isc
- NVD status
- Deferred
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.
Weaknesses (CWE)
- CWE-617 — Reachable Assertion
References
Scores
| Version | Score | Vector | Scored by |
|---|---|---|---|
| CVSS 3.1 | HIGH 7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H | isc |
| CVSS 3.1 | HIGH 7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H | NVD · security-officer@isc.org (Secondary) |
European references
- ENISA EUVD · EUVD-2025-21736
- GCVE · GCVE-0-2025-40777
CERT-FR advisories
- CERTFR-2025-AVI-0596 — Multiples vulnérabilités dans ISC BIND · cert.ssi.gouv.fr
Affected products
| Product | Versions |
|---|---|
| ISC · BIND 9 | affected 9.20.0 ≤ 9.20.10 ; affected 9.21.0 ≤ 9.21.9 ; affected 9.20.9-S1 ≤ 9.20.10-S1 ; unaffected 9.18.0 ≤ 9.18.37 ; unaffected 9.18.11-S1 ≤ 9.18.37-S1 |
Sources
| Source | Licence |
|---|---|
| CVE List (CVEProject cvelistV5) | CVE Program Terms of Use |
| EPSS (FIRST.org) | FIRST — attribution requested |
| ENISA EUVD | ENISA — reproduction authorised, source acknowledged |
| CERT-FR (ANSSI) | Licence Ouverte / Etalab 2.0 |
| NVD (NIST) via fkie-cad/nvd-json-data-feeds | Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD |