BIND 9 server memory exhaustion during GSS-API TKEY negotiation

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Summary

CVECVE-2026-3039
StatePUBLISHED
Assignerisc
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-05-20 13:16:23 UTC
Updated2026-07-15 02:20:56 UTC
DescriptionBIND 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.

Risk And Classification

Primary CVSS: v3.1 7.5 HIGH from ADP

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS: 0.000600000 probability, percentile 0.187840000 (date 2026-05-27)

Problem Types: CWE-771 | CWE-770 | CWE-771 CWE-771 Missing Reference to Active Allocated Resource | CWE-770 Allocation of Resources Without Limits or Throttling

VersionSourceTypeScoreSeverityVector
3.1ADPCVSS7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
3.1[email protected]Secondary7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
3.10b0ca135-0b70-47e7-9f44-1890c2a1c46cSecondary7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
3.1CNADECLARED7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Isc Bind All All All All
Application Isc Bind All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA ISC BIND 9 affected 9.0.0 9.16.50 custom Not specified
CNA ISC BIND 9 affected 9.18.0 9.18.48 custom Not specified
CNA ISC BIND 9 affected 9.20.0 9.20.22 custom Not specified
CNA ISC BIND 9 affected 9.21.0 9.21.21 custom Not specified
CNA ISC BIND 9 affected 9.9.3-S1 9.16.50-S1 custom Not specified
CNA ISC BIND 9 affected 9.18.11-S1 9.18.48-S1 custom Not specified
CNA ISC BIND 9 affected 9.20.9-S1 9.20.22-S1 custom Not specified
ADP Red Hat Red Hat Enterprise Linux 10 unaffected 32:9.18.33-15.el10_2.2 * rpm Not specified
ADP Red Hat Red Hat Enterprise Linux 8 unaffected 32:9.16.23-0.22.el8_10.6 * rpm Not specified
ADP Red Hat Red Hat Enterprise Linux 8 unaffected 32:9.11.36-16.el8_10.8 * rpm Not specified
ADP Red Hat Red Hat Enterprise Linux 9 unaffected 32:9.16.23-40.el9_8.2 * rpm Not specified
ADP Red Hat Red Hat Enterprise Linux 9 unaffected 32:9.18.29-14.el9_8.2 * rpm Not specified
ADP Red Hat Red Hat Hardened Images unaffected 9.18.49-1.hum1 * rpm Not specified
ADP Red Hat Red Hat Enterprise Linux 6 Not specified Not specified
ADP Red Hat Red Hat Enterprise Linux 7 Not specified Not specified
ADP Red Hat Red Hat Enterprise Linux 9 Not specified Not specified
ADP Red Hat Red Hat OpenShift Container Platform 4 Not specified Not specified

References

ReferenceSourceLinkTags
downloads.isc.org/isc/bind9/9.21.22 [email protected] downloads.isc.org Patch
access.redhat.com/errata/RHSA-2026:23360 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-3039.json 0b0ca135-0b70-47e7-9f44-1890c2a1c46c security.access.redhat.com
access.redhat.com/errata/RHSA-2026:24367 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
access.redhat.com/errata/RHSA-2026:24368 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
kb.isc.org/docs/cve-2026-3039 [email protected] kb.isc.org Vendor Advisory
access.redhat.com/security/cve/CVE-2026-3039 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
access.redhat.com/errata/RHSA-2026:24339 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
downloads.isc.org/isc/bind9/9.20.23 [email protected] downloads.isc.org Patch
bugzilla.redhat.com/show_bug.cgi 0b0ca135-0b70-47e7-9f44-1890c2a1c46c bugzilla.redhat.com
access.redhat.com/errata/RHSA-2026:24338 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
access.redhat.com/errata/RHSA-2026:20334 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
downloads.isc.org/isc/bind9/9.18.49 [email protected] downloads.isc.org Patch
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: ISC would like to thank Vitaly Simonovich for bringing this vulnerability to our attention. (en)

Additional Advisory Data

SourceTimeEvent
ADP2026-05-19T09:48:19.212ZReported to Red Hat.
ADP2026-05-21T12:24:11.051ZMade public.

Solutions

CNA: Upgrade to the patched release most closely related to your current version of BIND 9: 9.18.49, 9.20.23, 9.21.22, 9.18.49-S1, or 9.20.23-S1.

ADP: RHSA-2026:24338: Red Hat Enterprise Linux AppStream (v. 10), Red Hat Enterprise Linux CodeReady Linux Builder (v. 10)

ADP: RHSA-2026:24339: Red Hat Enterprise Linux AppStream (v. 8), Red Hat Enterprise Linux BaseOS (v. 8)

ADP: RHSA-2026:23360: Red Hat Enterprise Linux AppStream (v. 8), Red Hat Enterprise Linux CRB (v. 8)

ADP: RHSA-2026:24367: Red Hat Enterprise Linux AppStream (v. 9), Red Hat Enterprise Linux CodeReady Linux Builder (v. 9)

ADP: RHSA-2026:24368: Red Hat Enterprise Linux AppStream (v. 9), Red Hat Enterprise Linux CodeReady Linux Builder (v. 9)

ADP: RHSA-2026:20334: Red Hat Hardened Images

Workarounds

CNA: No workarounds known.

ADP: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability. Example: ```bash # Edit /etc/named.conf and remove or comment out lines related to tkey-gssapi-keytab or tkey-gssapi-credential. # For example, remove or comment out: # key "gssapi-key" { # algorithm GSSAPI; # secret "BASE64_ENCODED_KEY"; # }; # # Then reload the named service: systemctl reload named ``` Reloading the `named` service may cause a brief interruption in DNS resolution.

Exploits

CNA: We are not aware of any active exploits.

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