CVE-2025-40777 Affecting bind9 package, versions <1:9.20.4-3ubuntu1.2


Severity

Recommended
medium

Based on Ubuntu security rating.

Threat Intelligence

EPSS
0.02% (4th percentile)

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  • Snyk IDSNYK-UBUNTU2504-BIND9-10769989
  • published17 Jul 2025
  • disclosed16 Jul 2025

Introduced: 16 Jul 2025

NewCVE-2025-40777  (opens in a new tab)

How to fix?

Upgrade Ubuntu:25.04 bind9 to version 1:9.20.4-3ubuntu1.2 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream bind9 package and not the bind9 package as distributed by Ubuntu. See How to fix? for Ubuntu:25.04 relevant fixed versions and status.

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.

CVSS Base Scores

version 3.1