CVE-2019-6474: An oversight when validating incoming client requests can lead to a situation where the Kea server will exit when trying to restart
  • 28 Aug 2019
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CVE-2019-6474: An oversight when validating incoming client requests can lead to a situation where the Kea server will exit when trying to restart

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Article summary

CVE: CVE-2019-6474

Document Version: 2.0

Posting date: 28 August 2019

Program Impacted: Kea DHCP

Versions affected: 1.4.0 -> 1.5.0. Versions prior to 1.4.0 are considered "End of Life" and have not been tested for this vulnerability, though they are believed to be affected. Also affects development versions 1.6.0-beta1 and 1.6.0-beta2

Severity: Medium

Exploitable: From adjacent networks permitted to relay DHCP traffic to the Kea server


A missing check on incoming client requests can be exploited to cause a situation where the Kea server's lease storage contains leases which are rejected as invalid when the server tries to load leases from storage on restart. If the number of such leases exceeds a hard-coded limit in the Kea code, a server trying to restart will conclude that there is a problem with its lease store and give up.


Only Kea servers which use memfile storage for leases are affected by this vulnerability.

An attacker can exploit the missing check to deliberately create a situation where the server will not restart properly should it stop for any reason.

CVSS Score: 5.7


For more information on the Common Vulnerability Scoring System and to obtain your specific environmental score please visit:



Active exploits:

No known active exploits


Upgrade to a version of Kea containing a fix, available via

  • Kea 1.4.0-P2
  • Kea 1.5.0-P1
  • Kea 1.6.0

Document Revision History:

1.0 Advance Notification, 21 August 2019
2.0 Public disclosure, 28 August 2019

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