🛡️ CVE-2025-40777

🟠 CVSS 7.5 — High ✅ No Known Exploit CWE-617 NVD
7.5
CVSS Score
0 Low4 Medium7 High9 Critical10

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.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity none, availability high.

Affected software

CVE-2025-40777 is recorded against 1 package.

  • unknown

Timeline and source

Published on 16 July 2025 and last revised on 17 June 2026. No public exploit is currently recorded for this entry. Record sourced from NVD.

References

kb.isc.org
www.openwall.com

CVE-2025-40777 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity HIGH
CVSS Score 7.5
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CWE CWE-617
Public Exploit ✅ No
Source NVD
Published 2025-07-16
Updated 2026-08-11
Modified 2026-06-17
Fix URL N/A

Affected Packages

Software From version Fixed in
unknown — —

Similar Threats

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