{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-63874", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-07-19T07:54:57.017Z", "datePublished": "2026-07-19T14:18:41.907Z", "dateUpdated": "2026-08-05T12:36:47.817Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:36:47.817Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: mctp: usb: fix race between urb completion and rx_retry cancellation\n\nIt's possible that sequencing between setting ->stopped and cancelling\nthe rx_retry work (in ndo_stop) could leave us with an urb queued:\n\n T1: ndo_stop T2: rx_retry_work\n ------------ ----------------\n LD: ->stopped => false\n ST: ->stopped <= true\n usb_kill_urb()\n mctp_usb_rx_queue()\n usb_submit_urb()\n cancel_delayed_work_sync()\n\nThat urb completion can then re-schedule rx_retry_work.\n\nStrenghen the sequencing between the stop (preventing another requeue)\nand the cancel by updating both atomically under a new rx lock. After\nsetting ->rx_stopped, and cancelling pending work, we know that the\nrequeue cannot occur, so all that's left is killing any pending urb." } ], "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 race is hit in `mctp_usb_stop()` (`ndo_stop`) during netdev teardown, which is reachable via local RTNETLINK (`ip link set down`) or USB disconnect; it is not reachable from remote network input. Per the uncertainty rule, Local is chosen over Physical.\nAC:L - An attacker can control both sides of the race by inducing RX ENOMEM to schedule `rx_retry_work` (memory pressure) and concurrently triggering netdev stop/disconnect, retrying timing until the window between `stopped=true` and `cancel_delayed_work_sync()` is won.\nPR:L - Triggering `ndo_stop` through RTNETLINK requires `CAP_NET_ADMIN`, which is obtainable in an unprivileged user namespace; a physical USB disconnect path needs no software privileges, but PR:L is the higher-severity choice when uncertain.\nUI:N - Exploitation does not require any victim user action beyond the attacker’s own interface teardown/disconnect and memory-pressure timing.\nS:U - Impact is kernel memory corruption/UAF within the same kernel security boundary, not a cross-boundary escape such as guest-to-host or sandbox breakout.\nC:H - Winning the race leaves RX URBs/completions running after `usb_free_urb()` and `free_netdev()`, producing a use-after-free on `net_device`, `urb`, and `sk_buff` objects that can be turned into arbitrary kernel memory disclosure.\nI:H - The post-teardown UAF on heap-allocated driver/netdev/USB objects provides exploitable write primitives (re-submitted URBs, corrupted completion handlers) suitable for control-flow hijack and privilege escalation.\nA:H - The bug reliably causes kernel crashes (oops/panic) when freed URBs/netdevs are touched by completion handlers or rescheduled `rx_retry_work`, even before full exploitation." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/net/mctp/mctp-usb.c" ], "versions": [ { "version": "0791c0327a6e4e7691d6fc5ad334c215de04dcc9", "lessThan": "9c46f3ee1837f6881cb99a52ffecb2760f11dc73", "status": "affected", "versionType": "git" }, { "version": "0791c0327a6e4e7691d6fc5ad334c215de04dcc9", "lessThan": "d90feaa3f74bea8dafb6494631a194c70e547d94", "status": "affected", "versionType": "git" }, { "version": "0791c0327a6e4e7691d6fc5ad334c215de04dcc9", "lessThan": "54665dce982689e2fd99b32e9a0dcc204fda8a51", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/net/mctp/mctp-usb.c" ], "versions": [ { "version": "6.15", "status": "affected" }, { "version": "0", "lessThan": "6.15", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.36", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.0.13", "lessThanOrEqual": "7.0.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1", "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": "6.15", "versionEndExcluding": "6.18.36" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.15", "versionEndExcluding": "7.0.13" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.15", "versionEndExcluding": "7.1" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/9c46f3ee1837f6881cb99a52ffecb2760f11dc73" }, { "url": "https://git.kernel.org/stable/c/d90feaa3f74bea8dafb6494631a194c70e547d94" }, { "url": "https://git.kernel.org/stable/c/54665dce982689e2fd99b32e9a0dcc204fda8a51" } ], "title": "net: mctp: usb: fix race between urb completion and rx_retry cancellation", "x_generator": { "engine": "bippy-1.2.0" } } } }