Heap Use-After-Free Vulnerability in OpenWrt's odhcpd DHCP Server

CVE-2026-53918

What is CVE-2026-53918?

A heap use-after-free vulnerability exists in odhcpd, the DHCP server used by OpenWrt, affecting versions prior to 25.12. This vulnerability can be exploited by adjacent-network clients to manipulate the DHCPv6 IA handler. Upon sending a DHCPv6 REQUEST message that causes the first IA to be set and then fails a subsequent IA's on-link check, the system may free the lease for the first IA while trying to allocate a new one for a later IA. This results in the unauthorized access of previously freed memory, potentially leading to denial of service and confusion with the DHCPv6 Reconfigure keys. The issue has been addressed in version 25.12, ensuring greater security for OpenWrt users.

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