{"id":"CVE-2026-89554","revision":"c7fbf739fdf04e66bd03bb694d3f7c14","records":[{"revision":"c7fbf739fdf04e66bd03bb694d3f7c14","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-89554","aliases":[],"title":"mptcp: fix uninitialized local_id in syncookie MP_JOIN reconstruction","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nmptcp: fix uninitialized local_id in syncookie MP_JOIN reconstruction\n\nmptcp_token_join_cookie_init_state() restores remote_nonce, local_nonce,\nbackup, join_id, token and msk from the saved cookie entry when rebuilding\nthe request socket for a MP_JOIN 4th-ACK handled under SYN cookies, but it\ndoes not restore local_id, even though the SYN path saved it.\nsubflow_ulp_clone() then reads that uninitialized field and stores it as\nthe joined subflow's address-ID. Because the request-sock slab is\nSLAB_TYPESAFE_BY_RCU and not zeroed on allocation, the value is the stale\nbyte of a previously freed request socket, which an off-path peer can\ninfluence by sending concurrent MP_JOIN SYNs. This corrupts the path\nmanager's id-based subflow bookkeeping for the connection.\n\nRestore subflow_req->local_id from the cookie entry, as done for the other\nfields.","state":0,"publishedAt":"2026-09-11T19:44:27.586+00:00","modifiedAt":"2026-10-19T08:48:47.068+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"unaffected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"net/mptcp/syncookies.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"9466a1ccebbe54ac57fb8a89c2b4b854826546a8\",\n                            \"lessThan\": \"4534e0eead692bb069ad1e6a5a245fc2e2078300\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"9466a1ccebbe54ac57fb8a89c2b4b854826546a8\",\n                            \"lessThan\": \"63cacb05e51a1c6e1349d2e593d00fd6ef43def4\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"9466a1ccebbe54ac57fb8a89c2b4b854826546a8\",\n                            \"lessThan\": \"954b5ea836eb118d188975ced803448537ab8479\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"9466a1ccebbe54ac57fb8a89c2b4b854826546a8\",\n                            \"lessThan\": \"9df36a4846375a9b75bf42d77bfed216b0f366f9\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"9466a1ccebbe54ac57fb8a89c2b4b854826546a8\",\n                            \"lessThan\": \"64f2c5dd49b956a542c8c02b8dad5d262a462bba\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"9466a1ccebbe54ac57fb8a89c2b4b854826546a8\",\n                            \"lessThan\": \"51887ccd88791ddaa8755a7c614fda031ecf7982\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"9466a1ccebbe54ac57fb8a89c2b4b854826546a8\",\n                            \"lessThan\": \"bf19d166337c6488b39cb03eeeffb30a941d6326\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"9466a1ccebbe54ac57fb8a89c2b4b854826546a8\",\n                            \"lessThan\": \"b878dfdd12d7a5b8722a78d35e313506140ca3d9\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        }\n                    ]\n                }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"affected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"net/mptcp/syncookies.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"5.9\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \"0\",\n                            \"lessThan\": \"5.9\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"5.10.270\",\n                            \"lessThanOrEqual\": \"5.10.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"5.15.221\",\n                            \"lessThanOrEqual\": \"5.15.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.1.188\",\n                            \"lessThanOrEqual\": \"6.1.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.6.157\",\n                            \"lessThanOrEqual\": \"6.6.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.12.109\",\n                            \"lessThanOrEqual\": \"6.12.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.18.50\",\n                            \"lessThanOrEqual\": \"6.18.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.2.4\",\n                            \"lessThanOrEqual\": \"7.2.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.3\",\n                            \"lessThanOrEqual\": \"*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"original_commit_for_fix\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H","score":8.2,"severity":"HIGH"}],"references":["https://git.kernel.org/stable/c/4534e0eead692bb069ad1e6a5a245fc2e2078300","https://git.kernel.org/stable/c/63cacb05e51a1c6e1349d2e593d00fd6ef43def4","https://git.kernel.org/stable/c/954b5ea836eb118d188975ced803448537ab8479","https://git.kernel.org/stable/c/9df36a4846375a9b75bf42d77bfed216b0f366f9","https://git.kernel.org/stable/c/64f2c5dd49b956a542c8c02b8dad5d262a462bba","https://git.kernel.org/stable/c/51887ccd88791ddaa8755a7c614fda031ecf7982","https://git.kernel.org/stable/c/bf19d166337c6488b39cb03eeeffb30a941d6326","https://git.kernel.org/stable/c/b878dfdd12d7a5b8722a78d35e313506140ca3d9"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-89554","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-89554","identifiers":["CVE-2026-89554"]},"retained":false,"historicalAffected":[]}],"coverage":[]}