BIND Resolver Performance Issue in ISC BIND Software
CVE-2026-81736

7.5HIGH

Key Information:

Vendor

Isc
Status
Bind 9
Vendor
CVE Published:
16 September 2026

Badges

👾 Exploit Exists

What is CVE-2026-81736?

A performance vulnerability in ISC BIND occurs when a resolver with a cached tree of SVCB/HTTPS AliasMode records is queried for the root of that tree. In such cases, the resolver may utilize an excessive amount of CPU time to construct the response, leading to degraded performance. This issue primarily affects multiple versions of BIND 9, and administrators should ensure they are running the latest patched versions to mitigate potential impacts.

Affected Version(s)

BIND 9 9.18.0 <= 9.18.50

BIND 9 9.20.0 <= 9.20.27

BIND 9 9.21.0 <= 9.21.25

References

https://kb.isc.org/docs/cve-2026-81736
vendor-advisory
https://downloads.isc.org/isc/bind9/9.20.29
patch
https://downloads.isc.org/isc/bind9/9.21.26
patch

CVSS V3.1

Score:
7.5
Severity:
HIGH
Confidentiality:
None
Integrity:
None
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • 👾

    Exploit known to exist

  • Vulnerability published

  • Vulnerability Reserved

Credit

ISC would like to thank Henrique Pereira for bringing this vulnerability to our attention.
.