CVE-2026-53921
9.8 CRITICALpublic exploit availablePublished 2026-10-23 · Updated 2026-10-23
AI risk analysis
- Summary
- odhcpd contains a stack-based buffer overflow in its DHCPv6 IA response handler, where crafted requests with many IA options can write past a 512-byte stack buffer (pdbuf), enabling remote code execution as root on OpenWrt devices lacking modern mitigations.
- Exploitability
- Exploitation is straightforward for an unauthenticated attacker over the network via a single UDP packet, requiring only knowledge of the vulnerable service endpoint and no user interaction.
- Blast radius
- Successful exploitation grants full system compromise (CIA impact) on affected OpenWrt devices, with potential for persistent backdoor deployment or lateral movement within local networks.
- Detection
- No reliable host or network indicator is derivable from the published description.
- Prioritized remediation
- Upgrade to odhcpd version 25.12 or later.
Analysis generated locally by garnet-coder (no data left the box). AI-assisted — verify against primary sources before acting.
NVD 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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weaknesses
CWE-121
Public exploit & PoC references
- https://github.com/openwrt/odhcpd/commit/0320032ae313452f3c8cb8725c621dd06c36dc03
- https://github.com/openwrt/odhcpd/commit/03dacc23356b5789842b9d1bba0200fd005e35f3
- https://github.com/openwrt/odhcpd/commit/2a42d34c3615e2449ca273f673eee7c429d819a9
- https://github.com/openwrt/odhcpd/commit/6634b7a3c79c41a27687925c98c35c8aea2f2b5a
- https://github.com/openwrt/odhcpd/commit/d168c27fb6a55a07ac4c888e09ff2f41e263d7b7
- https://github.com/openwrt/odhcpd/commit/d329a15413387027453644cd363dca06ade28328
- https://github.com/openwrt/odhcpd/security/advisories/GHSA-7fwx-hhrg-3496
All references
- https://github.com/openwrt/odhcpd/commit/0320032ae313452f3c8cb8725c621dd06c36dc03
- https://github.com/openwrt/odhcpd/commit/03dacc23356b5789842b9d1bba0200fd005e35f3
- https://github.com/openwrt/odhcpd/commit/2a42d34c3615e2449ca273f673eee7c429d819a9
- https://github.com/openwrt/odhcpd/commit/6634b7a3c79c41a27687925c98c35c8aea2f2b5a
- https://github.com/openwrt/odhcpd/commit/d168c27fb6a55a07ac4c888e09ff2f41e263d7b7
- https://github.com/openwrt/odhcpd/commit/d329a15413387027453644cd363dca06ade28328
- https://github.com/openwrt/odhcpd/security/advisories/GHSA-7fwx-hhrg-3496
Source data: NVD (nvd.nist.gov), public domain. Exploit-DB.ai adds local AI analysis for defensive use only.
Related CVEs
- CRITICALCVE-2026-10133
- CRITICALCVE-2026-10137
- CRITICALCVE-2026-10139
- CRITICALCVE-2026-114382PoC
- CRITICALCVE-2026-40615
- CRITICALCVE-2026-41222
- CRITICALCVE-2026-42026
- CRITICALCVE-2026-10132
Related by shared AI tags and CWE weakness class. Browse the full archive.