CVE: CVE-2026-3608
Title: Stack overflow in Kea daemons
Document version: 2.0
Posting date: 25 March 2026
Program impacted: Kea
Versions affected:
Kea
- 2.6.0 -> 2.6.4
- 3.0.0 -> 3.0.2
Severity: High
Exploitable: Remotely
Description:
Sending a maliciously crafted message to the kea-ctrl-agent, kea-dhcp-ddns, kea-dhcp4, or kea-dhcp6 daemons over any configured API socket or HA listener can cause the receiving daemon to exit with a stack overflow error.
Impact:
Loss of DHCP services
CVSS Score: 7.5
CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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:L/PR:N/UI:N/S:U/C:N/I:N/A:H&version=3.1.
Workarounds:
Securing the API sockets with TLS, and requiring the client to authenticate with a certificate (mutual authentication), prevents the attacker from establishing an API connection to Kea. Set cert-required to true (the default) to require a client certificate. See: https://kea.readthedocs.io/en/stable/arm/security.html#tls-https-configuration
Active exploits:
We are not aware of any active exploits.
Solution:
Upgrade to the patched release most closely related to your current version of Kea:
- 2.6.5
- 3.0.3
Acknowledgments:
ISC would like to thank Ali Norouzi of Keysight for bringing this vulnerability to our attention.
Document revision history:
- 1.0 Early Notification, 18 March 2026
- 1.1 Added workaround, 20 March 2026
- 2.0 Public disclosure, 25 March 2026
Do you still have questions? Questions regarding this advisory should be mailed to kea-security@isc.org or posted as confidential GitLab issues at https://gitlab.isc.org/isc-projects/kea/-/issues/new?issue[confidential]=true.
Note:
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-2026-3608 is the complete and official security advisory document.
Legal Disclaimer:
Internet Systems Consortium (ISC) is providing this notice on an "AS IS" basis. No warranty or guarantee of any kind is expressed in this notice and none should be implied. ISC expressly excludes and disclaims any warranties regarding this notice or materials referred to in this notice, including, without limitation, any implied warranty of merchantability, fitness for a particular purpose, absence of hidden defects, or of non-infringement. Your use or reliance on this notice or materials referred to in this notice is at your own risk. ISC may change this notice at any time. A stand-alone copy or paraphrase of the text of this document that omits the document URL is an uncontrolled copy. Uncontrolled copies may lack important information, be out of date, or contain factual errors.