Is CVE-2025-40777 in the CISA KEV catalog?

No. CVE-2025-40777 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2025-40777?

CVE-2025-40777 has a CVSS v3 base score of 7.5 (HIGH).

What is the EPSS score for CVE-2025-40777?

CVE-2025-40777 has an EPSS score of 0.88% (54th percentile), estimating the probability of exploitation in the next 30 days.

CVE & CISA-KEV Catalog

CVE-2025-40777

HIGH

7.5

CVSS v3

NVD

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.

CWE-617

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityNone

AvailabilityHigh

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

Exploit Intelligence

0.88%probability of exploitation in 30 days

54thpercentile

Moderate risk: more likely to be exploited than 54% of all known CVEs.

References

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-11-04.