{"id":"CVE-2026-55606","title":"odhcpd: Stack buffer overread via DUID length endianness mismatch in memcmp()","summary":"odhcpd is the DHCPv6, DHCPv4, and router-advertisement server used by OpenWrt. In versions 25.12 and prior, odhcpd's DHCPv6 self-loop detection at dhcpv6.c:720 uses a network-byte-order DUID length value directly as the memcmp() size par…","severity":"medium","cvss":6.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L","cvssSource":"cna","cwe":["CWE-126"],"vendor":"openwrt","product":"odhcpd","affected":["odhcpd <= 25.12"],"published":"2026-10-23","updated":"2026-10-23","sourceUpdated":"2026-10-23T13:21:21.038Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-55606","references":[{"url":"https://github.com/openwrt/odhcpd/security/advisories/GHSA-x8x4-7gvf-gp45","label":"https://github.com/openwrt/odhcpd/security/advisories/GHSA-x8x4-7gvf-gp45"},{"url":"https://github.com/openwrt/odhcpd/pull/401","label":"https://github.com/openwrt/odhcpd/pull/401"},{"url":"https://github.com/openwrt/odhcpd/commit/6907f28f9ddeef9f69f5ee10bbc9ba8adc0ef57f","label":"https://github.com/openwrt/odhcpd/commit/6907f28f9ddeef9f69f5ee10bbc9ba8adc0ef57f"},{"url":"https://github.com/openwrt/odhcpd/commit/ed38cffa927d5fd450d20bfd3f7fb8d8e8fff301","label":"https://github.com/openwrt/odhcpd/commit/ed38cffa927d5fd450d20bfd3f7fb8d8e8fff301"}],"tags":["cve.org"],"ingestedAt":"2026-10-23T14:28:08.714Z","slug":"CVE-2026-55606","body":"## Overview\n\nodhcpd is the DHCPv6, DHCPv4, and router-advertisement server used by OpenWrt. In versions 25.12 and prior, odhcpd's DHCPv6 self-loop detection at dhcpv6.c:720 uses a network-byte-order DUID length value directly as the memcmp() size parameter. On little-endian hosts, this causes memcmp() to read far beyond the stack buffer — a single unauthenticated DHCPv6 packet triggers a 2560-byte overread from a 128-byte buffer. At time of publication, there are no publicly available patches.\n\n## Affected\n\n- `odhcpd <= 25.12`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":36,"depthScoreParts":{"impact":35.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}