CVE-2026-53918 odhcpd DHCPv6 IA dangling first pointer use-after-free
- Exploited in the wild
- Not known
- Fix
- None listed
What is CVE-2026-53918?
CVE-2026-53918 is a high-severity vulnerability in openwrt odhcpd, published on 23 Oct 2026.
Official description
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.
Which versions are affected by CVE-2026-53918?
How do I fix CVE-2026-53918?
No fix has been published for CVE-2026-53918 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-53918 being exploited?
There is no known exploitation of CVE-2026-53918 in the wild and no public exploit code.
Sources
Also known as GHSA-44ff-jcwh-wgc2.