Bind CVE-2026-94300: Concurrent GSS-TSIG messages corrupt memory

Title: Concurrent GSS-TSIG messages corrupt memory

Replaying GSS-TSIG signed UDP messages can result in memory corruption in "named". An attacker who can capture a previously signed UDP message can replay it while the negotiated TSIG key is still valid. By also sending crafted queries to a zone the attacker controls, the attacker may potentially achieve remote code execution.

Memory corruption, leading to program abort and/or potential remote code execution.

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

For more information on the Common Vulnerability Scoring System and to obtain your specific environmental score please visit: https://nvd.nist.gov/vuln-metrics/cvss/v3-calculator?vector=AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H&version=3.1.

Upgrade to the patched release most closely related to your current version of BIND 9:

BIND Supported Preview Edition is a special feature preview branch of BIND provided to eligible ISC support customers.

While this flaw was discovered in internal testing, ISC would like to thank Dave Aitel from OpenAI who independently discovered and responsibly reported the issue to ISC.

See our BIND 9 Security Vulnerability Matrix for a complete listing of security vulnerabilities and versions affected.

Questions regarding this advisory should be posted as confidential GitLab issues at:

https://gitlab.isc.org/isc-projects/bind9/-/issues/new?issue[confidential]=true

ISC patches only currently supported versions. When possible we indicate EOL versions affected. For current information on which versions are actively supported, please see https://www.isc.org/download/.

ISC Security Vulnerability Disclosure Policy:

Details of our current security advisory policy and practice can be found in the ISC Software Defect and Security Vulnerability Disclosure Policy at https://kb.isc.org/docs/aa-00861.

The Knowledgebase article https://kb.isc.org/docs/cve-2026-94300 is the complete and official security advisory document.

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