{"id":"CVE-2026-53920","title":"odhcpd DHCPv6 Short IA_NA/IA_PD Body Stack Disclosure","summary":"odhcpd is the DHCPv6, DHCPv4, and router-advertisement server used by OpenWrt. From version 17.01.0 to before version 25.12.3, odhcpd's DHCPv6 IA parser accepts an IA_NA or IA_PD option whose body is shorter than struct dhcpv6_ia_hdr, ca…","severity":"high","cvss":8.7,"cvssVector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N","cvssSource":"cna","cwe":["CWE-125","CWE-126","CWE-200","CWE-201"],"vendor":"openwrt","product":"odhcpd","affected":["odhcpd >= 17.01.0, < 25.12.3"],"ssvc":{"exploitation":"none","automatable":"yes","technicalImpact":"partial","timestamp":"2026-10-23T17:33:12.791918Z"},"published":"2026-10-23","updated":"2026-10-23","sourceUpdated":"2026-10-23T20:58:10.536Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-53920","references":[{"url":"https://github.com/openwrt/odhcpd/security/advisories/GHSA-p769-5v73-pc4f","label":"https://github.com/openwrt/odhcpd/security/advisories/GHSA-p769-5v73-pc4f"},{"url":"https://github.com/openwrt/odhcpd/commit/719fc3abc0d7e7059871f9f572fb05ada86b8ff2","label":"https://github.com/openwrt/odhcpd/commit/719fc3abc0d7e7059871f9f572fb05ada86b8ff2"},{"url":"https://github.com/openwrt/odhcpd/commit/f2275efc72a87a95f971f159babcbadc5d241d42","label":"https://github.com/openwrt/odhcpd/commit/f2275efc72a87a95f971f159babcbadc5d241d42"}],"tags":["cve.org"],"ingestedAt":"2026-10-23T14:28:08.713Z","slug":"CVE-2026-53920","body":"## Overview\n\nodhcpd is the DHCPv6, DHCPv4, and router-advertisement server used by OpenWrt. From version 17.01.0 to before version 25.12.3, odhcpd's DHCPv6 IA parser accepts an IA_NA or IA_PD option whose body is shorter than struct dhcpv6_ia_hdr, casts the option header to that full structure, and reads ia->iaid before proving that the IA body contains the IAID field. If an unauthenticated network-adjacent client places a zero-length or otherwise short IA option at the end of odhcpd's 8192-byte receive stack buffer, the IAID read crosses from data_buf into adjacent stack memory. The disclosed bytes are then reflected in the DHCPv6 reply IAID; prior ARM validation showed data_buf[8192:8196] disclosing the saved stack canary, and wider stack scans can leak ASLR-useful stack/process contents. This issue has been patched in version 25.12.3.\n\n## Affected\n\n- `odhcpd >= 17.01.0, < 25.12.3`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":48,"depthScoreParts":{"impact":47.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}