{"id":"CVE-2026-53918","state":"PUBLISHED","title":"odhcpd DHCPv6 IA dangling first pointer use-after-free","description":"odhcpd is the DHCPv6, DHCPv4, and router-advertisement server used by OpenWrt. Prior to version 25.12, odhcpd's DHCPv6 IA handler keeps a per-message `first` lease pointer so multiple IA options in one message reuse the same Reconfigure authentication key. A DHCPv6 REQUEST from an adjacent-network client can make the first IA set `first`, then make a later same-IAID IA fail the on-link check and free that same lease, leaving `first` dangling. A following IA in the same packet allocates a new lease and copies `first->key`, producing a 16-byte heap-use-after-free read. ASan confirms the UAF; native tracing shows the packet shape can deterministically reclaim the freed lease as the destination allocation, producing a zeroed Reconfigure key copy. The validated impact is unauthenticated adjacent-network denial of service and DHCPv6 Reconfigure/ForceRenew key confusion. Arbitrary PC control is not proven for this UAF alone. This issue has been patched in version 25.12.","publishedAt":"2026-10-23T13:21:00.665Z","updatedAt":"2026-10-30T17:42:21.816Z","severity":{"score":8.8,"label":"High","version":"4.0","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N","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-44ff-jcwh-wgc2","https://github.com/openwrt/odhcpd/commit/26b122007030ebf192376aff8f98d428b25e2a93","https://github.com/openwrt/odhcpd/commit/5b283832c0a77aed20f1cc384ffc40bc768b06e9"],"weaknesses":["CWE-416","CWE-672","CWE-825"],"ingestedAt":"2026-10-30T17:48:06.262Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/53xxx/CVE-2026-53918.json","commit":"55f09f8d4e130b1cf040d6352985ad794c15871d","baselineCommit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-53918","state":"PUBLISHED","datePublished":"2026-10-23T13:21:00.665Z","dateUpdated":"2026-10-30T17:42:21.816Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-06-11T15:46:12.315Z"},"containers":{"cna":{"title":"odhcpd DHCPv6 IA dangling first pointer use-after-free","descriptions":[{"lang":"en","value":"odhcpd is the DHCPv6, DHCPv4, and router-advertisement server used by OpenWrt. Prior to version 25.12, odhcpd's DHCPv6 IA handler keeps a per-message `first` lease pointer so multiple IA options in one message reuse the same Reconfigure authentication key. A DHCPv6 REQUEST from an adjacent-network client can make the first IA set `first`, then make a later same-IAID IA fail the on-link check and free that same lease, leaving `first` dangling. A following IA in the same packet allocates a new lease and copies `first->key`, producing a 16-byte heap-use-after-free read. ASan confirms the UAF; native tracing shows the packet shape can deterministically reclaim the freed lease as the destination allocation, producing a zeroed Reconfigure key copy. The validated impact is unauthenticated adjacent-network denial of service and DHCPv6 Reconfigure/ForceRenew key confusion. Arbitrary PC control is not proven for this UAF alone. This issue has been patched in version 25.12."}],"affected":[{"vendor":"openwrt","product":"odhcpd","versions":[{"version":"< 25.12","status":"affected"}]}],"references":[{"url":"https://github.com/openwrt/odhcpd/security/advisories/GHSA-44ff-jcwh-wgc2","name":"https://github.com/openwrt/odhcpd/security/advisories/GHSA-44ff-jcwh-wgc2","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/openwrt/odhcpd/commit/26b122007030ebf192376aff8f98d428b25e2a93","name":"https://github.com/openwrt/odhcpd/commit/26b122007030ebf192376aff8f98d428b25e2a93","tags":["x_refsource_MISC"]},{"url":"https://github.com/openwrt/odhcpd/commit/5b283832c0a77aed20f1cc384ffc40bc768b06e9","name":"https://github.com/openwrt/odhcpd/commit/5b283832c0a77aed20f1cc384ffc40bc768b06e9","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV4_0":{"attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"NONE","privilegesRequired":"NONE","userInteraction":"NONE","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"LOW","vulnAvailabilityImpact":"HIGH","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","subAvailabilityImpact":"NONE","baseScore":8.8,"baseSeverity":"HIGH","vectorString":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N","version":"4.0"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-416","lang":"en","description":"CWE-416: Use After Free","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-672","lang":"en","description":"CWE-672: Operation on a Resource after Expiration or Release","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-825","lang":"en","description":"CWE-825: Expired Pointer Dereference","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-10-23T13:21:00.665Z"},"source":{"advisory":"GHSA-44ff-jcwh-wgc2","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://github.com/openwrt/odhcpd/security/advisories/GHSA-44ff-jcwh-wgc2","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-10-30T17:42:15.930203Z","id":"CVE-2026-53918","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":"2026-10-30T17:42:21.816Z"}}]}}}