ZDF
Sign inSign up

Vulnerabilities

Vulnerability · CVE-2025-40777

If a caching resolver is configured with , and with set to (the only allowable value other than ), and if the resolver, in the process of resolving a query, encounters a CNAME chai

Published Jul 16, 2025 · catalog updated Oct 23, 2026 · ISC BIND 9

Check if you run it

No confirmed exploitation is on record for CVE-2025-40777. EPSS is 1.03%. Act only if a listed version of ISC BIND 9 is installed.

Gaps on this record

  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High7.5
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
1.03%
Remediation
Advisory link
Affected products
Debian:13 bind9 · Debian:14 bind9 · vendor ISC BIND 9 9.21.0 ≤9.21.9

If a caching resolver is configured with , and with set to (the only allowable value other than ), 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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • Debian:13 bind90 → 1:9.20.11-1
  • Debian:14 bind90 → 1:9.20.11-1
  • vendor ISC BIND 9 9.21.0 ≤9.21.99.21.0 ≤9.21.9

How to fix CVE-2025-40777

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2025-40777. EPSS is 1.03%. Act only if a listed version of ISC BIND 9 is installed.

Which versions are affected?

Compare what you have installed with ISC BIND 9 9.21.0 ≤9.21.9 9.21.0 ≤9.21.9. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

No weakness class is stored. EPSS 1.03%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

Debian security

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Jul 16, 2025 · EUVD

    Detected

    If a caching resolver is configured with , and with set to (the only allowable value other than ), 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 thro

  2. Nov 4, 2025 · EUVD

    Updated

    If a caching resolver is configured with , and with set to (the only allowable value other than ), 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 thro

  3. Oct 23, 2026 · Trivy Vulnerability DB

    Fix available

    bind9 fixed in 1:9.20.11-1; bind9 fixed in 1:9.20.11-1

  4. Oct 23, 2026 · Trivy Vulnerability DB

    Fix available

    bind9 fixed in 1:9.20.11-1

  5. Oct 23, 2026 · Trivy Vulnerability DB

    Updated

    If a caching resolver is configured with , and with set to (the only allowable value other than ), 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 thro

Sources

  • CVE.orgVulnerability recordCVE-2025-40777

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2025-40777

    30-day exploitation probability 1.03%

    first.org
  • EUVDVulnerability recordEUVD-2025-21736

    If a caching resolver is configured with , and with set to (the only allowable value other than ), 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

    euvd.enisa.europa.eu
  • Trivy Vulnerability DBPackage advisoryDEBIAN-CVE-2025-40777

    If a caching resolver is configured with , and with set to (the only allowable value other than ), 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

    osv.dev

References

Freshness

Last verified in this catalog Oct 23, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.