What’s Vulnerable › Vulnerabilities

CVE-2026-3039: BIND 9 server memory exhaustion during GSS-API TKEY negotiation

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-05-20 · updated 2026-09-17
• Weakness: CWE-771

Description

BIND servers that are configured to use TKEY-based authentication via GSS-API tokens are vulnerable to excessive memory consumption when receiving and processing maliciously-constructed packets. Typically these servers will be found in Active Directory integrated DNS deployments and/or Kerberos-secured DNS environments. This issue affects BIND 9 versions 9.0.0 through 9.16.50, 9.18.0 through 9.18.48, 9.20.0 through 9.20.22, 9.21.0 through 9.21.21, 9.9.3-S1 through 9.16.50-S1, 9.18.11-S1 through 9.18.48-S1, and 9.20.9-S1 through 9.20.22-S1.

Affected products

• ISC BIND: from 9.0.0 through 9.16.50; from 9.18.0 before 9.18.49; from 9.20.0 before 9.20.23; from 9.21.0 before 9.21.22 — fixed in 9.18.49, 9.20.23, 9.21.22

How to fix

Upgrade to a fixed version: ISC BIND 9.18.49, 9.20.23, 9.21.22. Check the vendor advisory for mitigations.

References

• https://downloads.isc.org/isc/bind9/9.18.49
• https://downloads.isc.org/isc/bind9/9.20.23
• https://downloads.isc.org/isc/bind9/9.21.22
• https://kb.isc.org/docs/cve-2026-3039
• https://access.redhat.com/errata/RHSA-2026:20334
• https://access.redhat.com/errata/RHSA-2026:23360
• https://access.redhat.com/errata/RHSA-2026:24338
• https://access.redhat.com/errata/RHSA-2026:24339
• https://access.redhat.com/errata/RHSA-2026:24367
• https://access.redhat.com/errata/RHSA-2026:24368
• https://access.redhat.com/errata/RHSA-2026:55441
• https://access.redhat.com/errata/RHSA-2026:57189

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