CVE-2026-53918

CVE-2026-53918 · odhcpd DHCPv6 IA dangling first pointer use-after-free

Cette page présente des faits issus de sources publiques. Consultez l’avis original avant toute mise à jour.

odhcpd is the DHCPv6, DHCPv4, and router-advertisement server used by OpenWrt. Prior to version 25.12, odhcpd's DHCPv6 IA handler keeps a per-message `first` lease pointer so multiple IA options in one message reuse the same Reconfigure authentication key. A DHCPv6 REQUEST from an adjacent-network client can make the first IA set `first`, then make a later same-IAID IA fail the on-link check and free that same lease, leaving `first` dangling. A following IA in the same packet allocates a new lease and copies `first->key`, producing a 16-byte heap-use-after-free read. ASan confirms the UAF; native tracing shows the packet shape can deterministically reclaim the freed lease as the destination allocation, producing a zeroed Reconfigure key copy. The validated impact is unauthenticated adjacent-network denial of service and DHCPv6 Reconfigure/ForceRenew key confusion. Arbitrary PC control is not proven for this UAF alone. This issue has been patched in version 25.12.

CVSS 8.8 · Élevée · EPSS 0,5%

Publication

2026-10-23T13:21:00.665Z

Mise à jour

2026-10-23T13:21:00.665Z

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