How severe is CVE-2025-40776?

CVE-2025-40776 has a CVSS 3.x base score of 8.6, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.

Is CVE-2025-40776 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (12th percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2025-40776?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2025-40776 have an EU (EUVD) identifier?

Yes. CVE-2025-40776 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-21705.

When was CVE-2025-40776 published?

CVE-2025-40776 was published on 2025-07-16 and last updated on 2026-06-17.

CVE-2025-40776

CVE-2025-40776 is a high-severity vulnerability with a CVSS 3.x base score of 8.6. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-349.

Key facts

Severity: High (CVSS 3.x base score 8.6)
EPSS exploit prediction: 0% (12th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2025-21705
Weakness: CWE-349
Published: 2025-07-16
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2025-40776?: 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.
How severe is CVE-2025-40776?: CVE-2025-40776 has a CVSS 3.x base score of 8.6, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.
Is CVE-2025-40776 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (12th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2025-40776?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2025-40776 have an EU (EUVD) identifier?: Yes. CVE-2025-40776 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-21705.
When was CVE-2025-40776 published?: CVE-2025-40776 was published on 2025-07-16 and last updated on 2026-06-17.

References

https://kb.isc.org/docs/cve-2025-40776

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