CVE-2025-40777
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CVSS Score
V3.1Attack Vector Metrics
Impact Metrics
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.
Available Exploits
Related News
BIND 9.20.x / 9.21.x ャserve-stale-enable yes stale-answer-client-timeout 0 (❼serve-stale-enable no stale-answer-client-timeout off )劫㍾羈 CNAME ァ若В羆阪絽悟篋 CVE-2025-40777 BIND 9.20.11 / 9.21.10 т信罩ｃ serve-stale-enable no stale-answer-client-timeout off ┃絎с …
EU Vulnerability Database
Monitored by ENISA for EU cybersecurity
ENISA Analysis
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.
Affected Products (ENISA)
ENISA Scoring
CVSS Score (3.1)
EPSS Score
ENISA References
Data provided by ENISA EU Vulnerability Database. Last updated: July 18, 2025
GitHub Security Advisories
Community-driven vulnerability intelligence from GitHub
Advisory Details
CVSS Scoring
CVSS Score
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
References
Advisory provided by GitHub Security Advisory Database. Published: July 16, 2025, Modified: July 16, 2025
Social Media Intelligence
Real-time discussions and threat intelligence from social platforms
Re: New BIND releases are available: 9.18.38, 9.20.11, 9.21.10 [https://lists.isc.org/pipermail/bind-announce/2025-July/001277.html](https://lists.isc.org/pipermail/bind-announce/2025-July/001277.html) >Wed Jul 16 13:32:45 UTC 2025 >In addition to bug fixes and feature improvements, these releases also contain fixes for security vulnerabilities (CVE-2025-40776, CVE-2025-40777), about which more information is provided in the following Security Advisories: [https://kb.isc.org/docs/cve-2025-40776](https://kb.isc.org/docs/cve-2025-40776) [https://kb.isc.org/docs/cve-2025-40777](https://kb.isc.org/docs/cve-2025-40777) \> On Jul …