CVE-2025-40777 Information

Jul 17, 2025 cve

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.

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Reference

https://kb.isc.org/docs/cve-2025-40777

Attack Complexity

LOW

Privileges Required

NONE

User Interaction Required

NONE

Scope

NONE

Confidentiality Impact

UNCHANGED

Integrity Impact

NONE

Availability Impact

NONE

Base Score

HIGH

Base Severity

7.5

CNNVD-202507-2133 (Published: 2025-07-16)

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