CVE-2026-53920

CVE-2026-53920 · odhcpd DHCPv6 Short IA_NA/IA_PD Body Stack Disclosure

This page contains facts from public vulnerability sources. Check the original advisory before updating.

odhcpd is the DHCPv6, DHCPv4, and router-advertisement server used by OpenWrt. From version 17.01.0 to before version 25.12.3, odhcpd's DHCPv6 IA parser accepts an IA_NA or IA_PD option whose body is shorter than struct dhcpv6_ia_hdr, casts the option header to that full structure, and reads ia->iaid before proving that the IA body contains the IAID field. If an unauthenticated network-adjacent client places a zero-length or otherwise short IA option at the end of odhcpd's 8192-byte receive stack buffer, the IAID read crosses from data_buf into adjacent stack memory. The disclosed bytes are then reflected in the DHCPv6 reply IAID; prior ARM validation showed data_buf[8192:8196] disclosing the saved stack canary, and wider stack scans can leak ASLR-useful stack/process contents. This issue has been patched in version 25.12.3.

CVSS 8.7 · High

Published

2026-10-23T13:20:48.045Z

Updated

2026-10-23T20:58:10.536Z

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