CVE: CVE-2025-11232
Title: Invalid characters cause assert
Document version: 2.0
Posting date: 29 October 2025
Program impacted: Kea
Versions affected:
Kea
- 3.0.1 -> 3.0.1
- 3.1.1 -> 3.1.2
Versions NOT affected:
Kea
- 2.6.0 -> 2.6.4
- 2.7.0 -> 2.7.9
- 3.0.0 -> 3.0.0
- 3.1.0 -> 3.1.0
(Versions prior to 2.6.0 were not assessed.)
Severity: High
Exploitable: Remotely
Description:
To trigger the issue, three configuration parameters must have specific settings: "hostname-char-set" must be left at the default setting, which is "[^A-Za-z0-9.-]"; "hostname-char-replacement" must be empty (the default); and "ddns-qualifying-suffix" must NOT be empty (the default is empty). DDNS updates do not need to be enabled for this issue to manifest. A client that sends certain option content would then cause kea-dhcp4 to exit unexpectedly.
Impact:
A denial of service from the repeated attacks against the Kea server
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:
Setting "hostname-char-replacement" to anything other than an empty value (suggestion: "x") is an effective workaround to this issue, regardless of other settings.
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:
- 3.0.2
- 3.1.3
Acknowledgments:
ISC would like to thank Siniša Uskoković and Ralf Steuer from Vienna University of Economics and Business for bringing this vulnerability to our attention.
Document revision history:
- 1.0 Early Notification, 22 October 2025
- 2.0 Public disclosure, 29 October 2025
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-2025-11232 is the complete and official security advisory document.
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