CVE-2026-81563 BIND 9 - Denial of Service

BIND 9 versions 9.18.0 through 9.18.50, 9.20.0 through 9.20.27, 9.21.0 through 9.21.25, 9.18.11-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.27-S1 contain a denial of service caused by improper deallocation of internal resources when processing SVCB/HTTPS AliasMode records referencing 14 or more ServiceMode records, letting attackers exhaust resolver resources, exploit requires repeated triggering of the condition.

CVSS base score 7.5 /10
High
CISA KEV
Not listed
Public exploit
None known
Authentication
Not required
EPSS
0.57% chance of exploitation in 30 days
View the NVD record ↗

Details

Type
Denial of Service
Impact
Denial Of Service
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Published
16 September 2026
Updated
15 October 2026
Weakness
CWE-401

Vendor fix

Update to a version later than 9.21.25 or the latest available version.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

References

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