CVE-2025-40777 (GCVE-0-2025-40777)

Vulnerability from cvelistv5 – Published: 2025-07-16 17:38 – Updated: 2025-11-04 21:10
VLAI
Title
A possible assertion failure when 'stale-answer-client-timeout' is set to '0'
Summary
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)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CWE
Assigner
isc
References
URL Tags
https://kb.isc.org/docs/cve-2025-40777 vendor-advisory
Impacted products
Vendor Product Version
ISC BIND 9 Affected: 9.20.0 , ≤ 9.20.10 (custom)
Affected: 9.21.0 , ≤ 9.21.9 (custom)
Affected: 9.20.9-S1 , ≤ 9.20.10-S1 (custom)
Unaffected: 9.18.0 , ≤ 9.18.37 (custom)
Unaffected: 9.18.11-S1 , ≤ 9.18.37-S1 (custom)
Create a notification for this product.
Date Public
2025-07-16 00:00
Show details on NVD website
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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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