{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-98253", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-25T10:25:14.331Z", "datePublished": "2026-10-06T08:45:20.077Z", "dateUpdated": "2026-10-19T09:16:24.567Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T09:16:24.567Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nRDMA/ucma: Serialize join and leave on copy_to_user failure\n\nrdma_join_multicast() queues RoCE work that later reads the ucma_multicast\nthrough event->param.ud.private_data, then list_add()s the CMA multicast\nat the head of id_priv->mc_list. rdma_leave_multicast() matches only by\nsockaddr and destroys the first hit.\n\nucma_process_join() used to drop ctx->mutex after a successful join and\nretake it only if copy_to_user() failed. Two concurrent JOIN_MCAST calls\nwith the same address can therefore insert a second CMA entry before the\nfirst thread's leave. leave then cancels the newer work and the older\nworker still dereferences the ucma_multicast that the first thread frees.\n\nKeep ctx->mutex held from rdma_join_multicast() through copy_to_user() and,\non -EFAULT, through rdma_leave_multicast() so leave cannot miss this join.\nDo not leave if join itself failed: that path never published this address\non mc_list, and a leave-by-addr would destroy an earlier successful join." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The bug is reached by write() of RDMA_USER_CM_CMD_JOIN_MCAST/JOIN_IP_MCAST on the local char device /dev/infiniband/rdma_cm into ucma_process_join(). The trigger is local: two racing joins and a bad response pointer. No remote peer supplies the data that causes it, so AV:L.\nAC:L - The attacker drives every part of the race. They make copy_to_user() fail with a bad cmd->response pointer, and a second thread issues JOIN_MCAST for the same address while ctx->mutex is dropped. rdma_leave_multicast() then destroys the newer mc_list head and cancels the wrong iboe_join work. The attempt can be repeated until it wins.\nPR:L - rdma_cm is created with mode 0666 and ucma_write() does no capability check. Any local user on a host with a RoCE port can create a UD cm_id, bind it and join multicast. An unprivileged user cannot create a soft-RoCE device, because nldev NEWLINK needs CAP_NET_ADMIN in the initial namespace, so the RoCE port must already exist.\nUI:N - The attacker triggers the bug entirely through their own writes on an rdma_cm file descriptor they opened. No other user or administrator has to act.\nS:U - The freed ucma_multicast and the corrupted kernel heap are in the same kernel security authority. This is local kernel memory corruption, not a VM or IOMMU boundary crossing.\nC:H - cma_iboe_join_work_handler() calls ucma_create_uevent() on the freed ucma_multicast, reading mc->uid and mc->id into the event that GET_EVENT copies to userspace. If the freed slot is reclaimed with sprayed objects, this use-after-free gives a read primitive.\nI:H - uevent->mc keeps a pointer to the freed ucma_multicast, and ucma_get_event() then runs uevent->mc->events_reported++. That is an attacker-timed write into freed and reclaimable slab memory, usable to corrupt an object sprayed into the slot.\nA:H - The use-after-free of ucma_multicast in the RoCE join worker and in ucma_get_event() can corrupt the slab or oops the kernel, crashing the host. Syzbot reported this bug (extid a6ffe86390c8a6afc818)." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/infiniband/core/ucma.c" ], "versions": [ { "version": "60d613b39e8d0c9f3b526e9c96445422b4562d76", "lessThan": "29b9ed83d8bfab5c6e11fcbf1aa836aa4ae26cb9", "status": "affected", "versionType": "git" }, { "version": "fe454dc31e84f8c14cb8942fcb61666c9f40745b", "lessThan": "52172e11bd074ccaded21740ffeb67123f01dd00", "status": "affected", "versionType": "git" }, { "version": "fe454dc31e84f8c14cb8942fcb61666c9f40745b", "lessThan": "01e29d0d78a8f66f221625720a04939eef5ec1f6", "status": "affected", "versionType": "git" }, { "version": "fe454dc31e84f8c14cb8942fcb61666c9f40745b", "lessThan": "ae805d204cf1f15b87d1bf3529b4c649f3519420", "status": "affected", "versionType": "git" }, { "version": "fe454dc31e84f8c14cb8942fcb61666c9f40745b", "lessThan": "43c4e24bd10370fc976f6220518049ce71419399", "status": "affected", "versionType": "git" }, { "version": "fe454dc31e84f8c14cb8942fcb61666c9f40745b", "lessThan": "01cbdb724c584d7772fd25af2e4dfdf8527ce0d5", "status": "affected", "versionType": "git" }, { "version": "fe454dc31e84f8c14cb8942fcb61666c9f40745b", "lessThan": "83610ee5e498fa5bfcb80031d2b959baea276bf6", "status": "affected", "versionType": "git" }, { "version": "fe454dc31e84f8c14cb8942fcb61666c9f40745b", "lessThan": "662ade4de9ff5eceb0820a9f8e9fac70ba6a815b", "status": "affected", "versionType": "git" }, { "version": "a3262b3884dd67b4c5632ce7cdf9cff9d1a575d4", "status": "affected", "versionType": "git" }, { "version": "5.10.20", "lessThan": "5.10.271", "status": "affected", "versionType": "semver" }, { "version": "5.11.3", "lessThan": "5.12", "status": "affected", "versionType": "semver" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/infiniband/core/ucma.c" ], "versions": [ { "version": "5.12", "status": "affected" }, { "version": "0", "lessThan": "5.12", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.271", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.222", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.189", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.158", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.112", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.54", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2.8", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.3", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.10.20", "versionEndExcluding": "5.10.271" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.12", "versionEndExcluding": "5.15.222" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.12", "versionEndExcluding": "6.1.189" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.12", "versionEndExcluding": "6.6.158" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.12", "versionEndExcluding": "6.12.112" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.12", "versionEndExcluding": "6.18.54" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.12", "versionEndExcluding": "7.2.8" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.12", "versionEndExcluding": "7.3" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.11.3" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/29b9ed83d8bfab5c6e11fcbf1aa836aa4ae26cb9" }, { "url": "https://git.kernel.org/stable/c/52172e11bd074ccaded21740ffeb67123f01dd00" }, { "url": "https://git.kernel.org/stable/c/01e29d0d78a8f66f221625720a04939eef5ec1f6" }, { "url": "https://git.kernel.org/stable/c/ae805d204cf1f15b87d1bf3529b4c649f3519420" }, { "url": "https://git.kernel.org/stable/c/43c4e24bd10370fc976f6220518049ce71419399" }, { "url": "https://git.kernel.org/stable/c/01cbdb724c584d7772fd25af2e4dfdf8527ce0d5" }, { "url": "https://git.kernel.org/stable/c/83610ee5e498fa5bfcb80031d2b959baea276bf6" }, { "url": "https://git.kernel.org/stable/c/662ade4de9ff5eceb0820a9f8e9fac70ba6a815b" } ], "title": "RDMA/ucma: Serialize join and leave on copy_to_user failure", "x_generator": { "engine": "bippy-1.2.0" } } } }