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.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Privileges Required
None
No privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
High
Complete data leak
Integrity
High
Complete data modification
Availability
High
Complete denial of service
CVSS Vector v3.1
Weakness Type (CWE)
References 7
https://github.com/openwrt/odhcpd/commit/0320032ae313452f3c8cb8725c621dd06c36dc…
security-advisories@github.com
https://github.com/openwrt/odhcpd/commit/03dacc23356b5789842b9d1bba0200fd005e35…
security-advisories@github.com
https://github.com/openwrt/odhcpd/commit/2a42d34c3615e2449ca273f673eee7c429d819…
security-advisories@github.com
https://github.com/openwrt/odhcpd/commit/6634b7a3c79c41a27687925c98c35c8aea2f2b…
security-advisories@github.com
https://github.com/openwrt/odhcpd/commit/d168c27fb6a55a07ac4c888e09ff2f41e263d7…
security-advisories@github.com
https://github.com/openwrt/odhcpd/commit/d329a15413387027453644cd363dca06ade283…
security-advisories@github.com
https://github.com/openwrt/odhcpd/security/advisories/GHSA-7fwx-hhrg-3496
security-advisories@github.com