{"id":"CVE-2023-54085","state":"PUBLISHED","title":"mptcp: fix NULL pointer dereference on fastopen early fallback","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nmptcp: fix NULL pointer dereference on fastopen early fallback\n\nIn case of early fallback to TCP, subflow_syn_recv_sock() deletes\nthe subflow context before returning the newly allocated sock to\nthe caller.\n\nThe fastopen path does not cope with the above unconditionally\ndereferencing the subflow context.","publishedAt":"2025-12-24T13:06:16.161Z","updatedAt":"2026-10-15T21:41:39.088Z","severity":{"score":7.5,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"36b122baf6a8bd46b4a591f12f4ed17b22257408","status":"affected","lessThan":"95135835519b0ab931c39908b2c99e9fb3c9068b","versionType":"git"},{"version":"36b122baf6a8bd46b4a591f12f4ed17b22257408","status":"affected","lessThan":"c0ff6f6da66a7791a32c0234388b1bdc00244917","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/mptcp/fastopen.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.2","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.2","versionType":"semver"},{"version":"6.2.12","status":"unaffected","lessThanOrEqual":"6.2.*","versionType":"semver"},{"version":"6.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/mptcp/fastopen.c"]}],"references":["https://git.kernel.org/stable/c/95135835519b0ab931c39908b2c99e9fb3c9068b","https://git.kernel.org/stable/c/c0ff6f6da66a7791a32c0234388b1bdc00244917"],"weaknesses":[],"ingestedAt":"2026-10-29T20:06:42.242Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2023/54xxx/CVE-2023-54085.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2023-54085","state":"PUBLISHED","datePublished":"2025-12-24T13:06:16.161Z","dateUpdated":"2026-10-15T21:41:39.088Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2025-12-24T13:02:52.515Z"},"containers":{"cna":{"title":"mptcp: fix NULL pointer dereference on fastopen early fallback","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nmptcp: fix NULL pointer dereference on fastopen early fallback\n\nIn case of early fallback to TCP, subflow_syn_recv_sock() deletes\nthe subflow context before returning the newly allocated sock to\nthe caller.\n\nThe fastopen path does not cope with the above unconditionally\ndereferencing the subflow context."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"36b122baf6a8bd46b4a591f12f4ed17b22257408","status":"affected","lessThan":"95135835519b0ab931c39908b2c99e9fb3c9068b","versionType":"git"},{"version":"36b122baf6a8bd46b4a591f12f4ed17b22257408","status":"affected","lessThan":"c0ff6f6da66a7791a32c0234388b1bdc00244917","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/mptcp/fastopen.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.2","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.2","versionType":"semver"},{"version":"6.2.12","status":"unaffected","lessThanOrEqual":"6.2.*","versionType":"semver"},{"version":"6.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/mptcp/fastopen.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/95135835519b0ab931c39908b2c99e9fb3c9068b"},{"url":"https://git.kernel.org/stable/c/c0ff6f6da66a7791a32c0234388b1bdc00244917"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","baseScore":7.5,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:N - The crash is triggered entirely by a received TCP SYN packet with fastopen data arriving at an MPTCP listening socket, processed in the TCP input path (`tcp_conn_request`). Any routable remote peer can reach it.\nAC:L - The attacker fully controls the trigger — a TFO SYN with data and no MPTCP options deterministically causes `subflow_ulp_clone()` to drop the context and `subflow_prep_synack()` to pass NULL; there is no race, no memory-layout dependency, and the TFO cookie is freely obtainable from a prior normal connection.\nPR:N - No credentials or prior authentication are required; the fault occurs during connection establishment, before any application-level handshake, on a socket that has not yet been accepted.\nUI:N - Exploitation requires only that the attacker send packets to the listening port; no action by any local user or administrator is needed at attack time.\nS:U - The NULL dereference occurs in the kernel's own network stack and affects only the kernel's security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:N - The faulting access is a load of `subflow->tcp_sock` at a fixed small offset from NULL, which aborts immediately; no attacker-controlled data is read back or disclosed.\nI:N - Execution aborts on the first NULL load before `subflow->is_mptfo = 1` or any queue manipulation, so no kernel memory is modified and no control-flow primitive is obtained.\nA:H - The dereference at NULL+~208 bytes is always unmapped and occurs in NET_RX softirq context, so `oops_end()` takes the `in_interrupt()` path and issues `panic(\"Fatal exception in interrupt\")` — a guaranteed, remotely repeatable full system crash."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T09:17:06.087Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.2","versionEndExcluding":"6.2.12"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.2","versionEndExcluding":"6.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2023-54085","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"version":"2.0.3","timestamp":"2026-10-15T21:38:15.912200Z"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-15T21:41:39.088Z"}}]}}}