{"id":"CVE-2026-55606","state":"PUBLISHED","title":"odhcpd: Stack buffer overread via DUID length endianness mismatch in memcmp()","description":"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 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.","publishedAt":"2026-10-23T13:21:21.038Z","updatedAt":"2026-10-29T17:43:41.478Z","severity":{"score":6.5,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L","source":"GitHub_M"},"assigner":"GitHub_M","products":["openwrt odhcpd"],"affected":[{"vendor":"openwrt","product":"odhcpd","versions":[{"version":"<= 25.12","status":"affected"}]}],"references":["https://github.com/openwrt/odhcpd/security/advisories/GHSA-x8x4-7gvf-gp45","https://github.com/openwrt/odhcpd/pull/401","https://github.com/openwrt/odhcpd/commit/6907f28f9ddeef9f69f5ee10bbc9ba8adc0ef57f","https://github.com/openwrt/odhcpd/commit/ed38cffa927d5fd450d20bfd3f7fb8d8e8fff301"],"weaknesses":["CWE-126"],"ingestedAt":"2026-10-29T20:12:24.861Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/55xxx/CVE-2026-55606.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-55606","state":"PUBLISHED","datePublished":"2026-10-23T13:21:21.038Z","dateUpdated":"2026-10-29T17:43:41.478Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-06-16T23:31:22.445Z"},"containers":{"cna":{"title":"odhcpd: Stack buffer overread via DUID length endianness mismatch in memcmp()","descriptions":[{"lang":"en","value":"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 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."}],"affected":[{"vendor":"openwrt","product":"odhcpd","versions":[{"version":"<= 25.12","status":"affected"}]}],"references":[{"url":"https://github.com/openwrt/odhcpd/security/advisories/GHSA-x8x4-7gvf-gp45","name":"https://github.com/openwrt/odhcpd/security/advisories/GHSA-x8x4-7gvf-gp45","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/openwrt/odhcpd/pull/401","name":"https://github.com/openwrt/odhcpd/pull/401","tags":["x_refsource_MISC"]},{"url":"https://github.com/openwrt/odhcpd/commit/6907f28f9ddeef9f69f5ee10bbc9ba8adc0ef57f","name":"https://github.com/openwrt/odhcpd/commit/6907f28f9ddeef9f69f5ee10bbc9ba8adc0ef57f","tags":["x_refsource_MISC"]},{"url":"https://github.com/openwrt/odhcpd/commit/ed38cffa927d5fd450d20bfd3f7fb8d8e8fff301","name":"https://github.com/openwrt/odhcpd/commit/ed38cffa927d5fd450d20bfd3f7fb8d8e8fff301","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"LOW","baseScore":6.5,"baseSeverity":"MEDIUM","confidentialityImpact":"LOW","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-126","lang":"en","description":"CWE-126: Buffer Over-read","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-10-23T13:21:21.038Z"},"source":{"advisory":"GHSA-x8x4-7gvf-gp45","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://github.com/openwrt/odhcpd/security/advisories/GHSA-x8x4-7gvf-gp45","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-10-29T17:43:15.504706Z","id":"CVE-2026-55606","options":[{"Exploitation":"poc"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-29T17:43:41.478Z"}}]}}}