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VulnerabilityPublished Updated

CVE-2026-3039: ISC BIND 9 · Missing Reference to Active Allocated Resource

Affects ISC BIND 9Source CVE Database V5

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Not known to be exploited · CVSS 7.5 High.

Data as of 29 Oct 2026, 19:04 UTC

CVSS 3.1 base score
7.5High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
1.0% chance of exploitation in 30 days – higher than 65% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 20 May 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.

What to do

Affected software

ProductAffectedFixed in
ISCBIND 9Affected
  • >=9.0.0 <=9.16.50
  • >=9.18.0 <=9.18.48
  • >=9.20.0 <=9.20.22
  • >=9.21.0 <=9.21.21
  • >=9.9.3-S1 <=9.16.50-S1
  • >=9.18.11-S1 <=9.18.48-S1
  • >=9.20.9-S1 <=9.20.22-S1
Fixed in–
GitHubisc/bind9pkg:github/isc/bind9Other threatsAffected
  • 9.0.0 – 9.21.0
7 affected builds
Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A security update addressing this vulnerability is available from Red Hat for affected BIND 9 versions as part of Red Hat Enterprise Linux 10 updates. Users should apply these official patches promptly. If patching is not immediately possible, a mitigation is to disable or remove TKEY-GSSAPI-related configuration lines (e.g., 'tkey-gssapi-keytab' or 'tkey-gssapi-credential') in the named.conf file and reload the named service, noting this may cause brief DNS resolution interruptions. No other mitigations meeting Red Hat's criteria are currently available.

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.

References

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