CVE-2026-53921

Published: Oct 23, 2026Modified: Oct 23, 2026Deferred

9.8

Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Exploitability: 3.9 / Impact: 5.9

Source: security-advisories@github.com (Secondary)

Description

odhcpd is the DHCPv6, DHCPv4, and router-advertisement server used by OpenWrt. Prior to version 25.12, odhcpd's DHCPv6 IA response handler writes past the end of a fixed 512-byte stack buffer (pdbuf) when a single DHCPv6 REQUEST carries enough IA options to nearly exhaust the reply space. Two independent overflow sites exist in the same call chain, both reachable from the network via a single unauthenticated UDP packet. odhcpd runs as root on OpenWrt; embedded targets often lack stack canaries and ASLR, making code execution realistic. This issue has been patched in version 25.12.

Related CWEs

Stack-based Buffer Overflow

A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).

References (7)

https://github.com/openwrt/odhcpd/commit/0320032ae313452f3c8cb8725c621dd06c36dc03

Source: security-advisories@github.com

https://github.com/openwrt/odhcpd/commit/03dacc23356b5789842b9d1bba0200fd005e35f3

Source: security-advisories@github.com

https://github.com/openwrt/odhcpd/commit/2a42d34c3615e2449ca273f673eee7c429d819a9

Source: security-advisories@github.com

https://github.com/openwrt/odhcpd/commit/6634b7a3c79c41a27687925c98c35c8aea2f2b5a

Source: security-advisories@github.com

https://github.com/openwrt/odhcpd/commit/d168c27fb6a55a07ac4c888e09ff2f41e263d7b7

Source: security-advisories@github.com

https://github.com/openwrt/odhcpd/commit/d329a15413387027453644cd363dca06ade28328

Source: security-advisories@github.com

https://github.com/openwrt/odhcpd/security/advisories/GHSA-7fwx-hhrg-3496

Source: security-advisories@github.com

Timeline

No history available yet.