CVE-2025-40776

Birthday Attack against Resolvers supporting ECS

State: Published
Severity: 8.6 High
Published: Jul 16, 2025
Updated: Jul 22, 2025
Reserved: Apr 16, 2025

Description

A `named` caching resolver that is configured to send ECS (EDNS Client Subnet) options may be vulnerable to a cache-poisoning attack. This issue affects BIND 9 versions 9.11.3-S1 through 9.16.50-S1, 9.18.11-S1 through 9.18.37-S1, and 9.20.9-S1 through 9.20.10-S1.

Scores

CVSS	Score	Vector	Source
3.1	8.6 High	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N	isc

Weaknesses

CWE-349 Acceptance of Extraneous Untrusted Data With Trusted Data

Affected Products

Product	Versions
BIND 9ISC	9.11.3-S1 through 9.16.50-S1Affected 9.18.11-S1 through 9.18.37-S1Affected 9.20.9-S1 through 9.20.10-S1Affected 9.0.0 through 9.20.10Not affected

References

CVE-2025-40776vendor-advisory

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