What is CVE-2025-40777?

CVE-2025-40777 is a high-severity vulnerability in Isc Bind 9, classified under Reachable Assertion. CVSS score: 7.5/10. Published 2025-07-16.

How severe is CVE-2025-40777?

High severity. CVSS v3 base score is 7.5 out of 10.

Is CVE-2025-40777 known to be exploited?

1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Vulnerability in Isc Bind 9

CVE-2025-40777

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, enco…

EPSS: 0.001 (27.5th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

Affected products

Isc Bind 9 — versions 9.20.0, 9.21.0, 9.20.9-S1

Weakness classification (CWE)

CWE-617 — Reachable Assertion

Public proof-of-concept exploits

8-cm/kube-dump

References

CVE-2025-40777 (vendor-advisory)

Frequently asked questions

What is CVE-2025-40777?: CVE-2025-40777 is a high-severity vulnerability in Isc Bind 9, classified under Reachable Assertion. CVSS score: 7.5/10. Published 2025-07-16.
How severe is CVE-2025-40777?: High severity. CVSS v3 base score is 7.5 out of 10.
Is CVE-2025-40777 known to be exploited?: 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.