CVE-2026-53921
CRITICAL
9,8
Source: [email protected]
Attack Vector: network
Attack Complexity: low
Privileges Required: none
User Interaction: none
Scope: unchanged
Confidentiality: high
Integrity: high
Availability: high
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.
121
Stack-based Buffer Overflow
DraftCommon Consequences
Security Scopes Affected:
Availability
Integrity
Confidentiality
Access Control
Other
Potential Impacts:
Modify Memory
Dos: Crash, Exit, Or Restart
Dos: Resource Consumption (Cpu)
Dos: Resource Consumption (Memory)
Execute Unauthorized Code Or Commands
Bypass Protection Mechanism
Other
Applicable Platforms
Languages:
Memory-Unsafe, C, C++
https://github.com/openwrt/odhcpd/commit/0320032ae313452f3c8cb8725c621dd06c36dc…
https://github.com/openwrt/odhcpd/commit/03dacc23356b5789842b9d1bba0200fd005e35…
https://github.com/openwrt/odhcpd/commit/2a42d34c3615e2449ca273f673eee7c429d819…
https://github.com/openwrt/odhcpd/commit/6634b7a3c79c41a27687925c98c35c8aea2f2b…
https://github.com/openwrt/odhcpd/commit/d168c27fb6a55a07ac4c888e09ff2f41e263d7…
https://github.com/openwrt/odhcpd/commit/d329a15413387027453644cd363dca06ade283…
https://github.com/openwrt/odhcpd/security/advisories/GHSA-7fwx-hhrg-3496