Buffer Overflow Vulnerability in odhcpd by OpenWrt

CVE-2026-53920

What is CVE-2026-53920?

The odhcpd DHCPv6 and DHCPv4 server used in OpenWrt versions 17.01.0 to before 25.12.3 has a vulnerability allowing an unauthenticated network-adjacent client to exploit the IA parser. Specifically, if a client sends an IA_NA or IA_PD option with a body shorter than required, it can cause a read out of bounds from the receive stack buffer. This flaw can lead to the disclosure of sensitive information stored in memory, reflecting unintended data in DHCPv6 replies, such as stack canary values and other critical system information.

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