{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-72121", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-08-09T03:40:39.907Z", "datePublished": "2026-08-15T05:52:59.959Z", "dateUpdated": "2026-08-19T16:36:16.520Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-19T16:36:16.520Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ncan: bcm: add locking when updating filter and timer values\n\nKCSAN detected a simultaneous access to timer values that can be\noverwritten in bcm_rx_setup() when updating timer and filter content\nwhile bcm_rx_handler(), bcm_rx_timeout_handler() or bcm_rx_thr_handler()\nrun concurrently on incoming CAN traffic.\n\nProtect the timer (ival1/ival2/kt_ival1/kt_ival2/kt_lastmsg) and filter\n(nframes/flags/frames/last_frames) updates in bcm_rx_setup() with a new\nper-op bcm_rx_update_lock, taken with the matching scope in the RX\nhandlers. memcpy_from_msg() is staged into a temporary buffer before the\nlock is taken, since it can sleep and must not run under a spinlock.\n\nhrtimer_cancel() is always called without bcm_rx_update_lock held, since\nbcm_rx_timeout_handler()/bcm_rx_thr_handler() take the same lock and a\nrunning callback would otherwise deadlock against the canceller.\n\nAlso close a related race: bcm_rx_setup() cleared the RTR flag in the\nstored reply frame's can_id as a separate, unprotected step after the\nframe content was already installed, so a concurrent bcm_rx_handler()\ncould transmit a stale reply with CAN_RTR_FLAG still set. Fold that\nnormalization into the initial frame preparation instead (on the staged\nbuffer for updates, directly on op->frames pre-registration for new\nops), so the installed frame is always atomically self-consistent.\n\nbcm_rx_handler()'s RX_RTR_FRAME check now takes a lock-protected\nsnapshot of op->flags before deciding whether to call bcm_can_tx(),\nbut does not hold the lock across that call.\n\nAlso take a lock-protected snapshot of the currframe in bcm_can_tx()\nto avoid partly overwrites by content updates in bcm_tx_setup().\nFinally check if a TX_RESET_MULTI_IDX/SETTIMER might have reset\nop->currframe between the two locked sections in bcm_can_tx().\n\nOmit calling hrtimer_forward() with zero interval in bcm_rx_thr_handler().\nkt_ival2 may have been concurrently cleared by bcm_rx_setup() before it\ncancels this timer, so check kt_ival2 inside the bcm_rx_update_lock." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 8.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:A - The race is driven by concurrent CAN frame reception in bcm_rx_handler()/timer callbacks on a shared CAN segment (automotive OBD/ECU bus, factory controllers, CAN-USB adapters), an adjacent broadcast medium comparable to Bluetooth/WiFi segment access.\nAC:L - An attacker controls both race sides by flooding RX_SETUP via sendmsg while concurrently injecting matching CAN frames or armed timers; syzbot reliably reproduced the KCSAN race without timing conditions beyond attacker control.\nPR:N - CAN_BCM sockets impose no capability checks in can_create()/bcm_sendmsg(), and a bus participant can trigger the RX handler path without any Linux credentials while racing BCM configuration updates from local services.\nUI:N - Exploitation requires no victim interaction beyond normal background CAN/BCM activity on systems that already use the Broadcast Manager for monitoring or diagnostics.\nS:U - Impact is confined to kernel memory corruption and privilege boundaries within the same host; this is not a VM escape, IOMMU bypass, or cross-authority sandbox breakout.\nC:H - Unlocked concurrent updates to nframes/flags/frames/last_frames permit torn reads and out-of-bounds accesses in handler loops and timeout memset, matching the prior BCM race class that produced KASAN slab-out-of-bounds reads.\nI:H - Partial overwrites of op->frames during bcm_can_tx(), stale RTR replies transmitted on the bus, and size-mismatched memset/memcpy against concurrently shrinking buffers enable arbitrary CAN injection and kernel heap corruption.\nA:H - Concurrent timer corruption (hrtimer_forward with zero kt_ival2), torn structure fields, and heap corruption from racing memset/copy operations can cause kernel oops, panic, or sustained denial of service on CAN-equipped systems." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/can/bcm.c" ], "versions": [ { "version": "7595de7bc56e0e52b74e56c90f7e247bf626d628", "lessThan": "96994180bd7b248b0cc698afe926e23fc1bda59b", "status": "affected", "versionType": "git" }, { "version": "fbd8fdc2b218e979cfe422b139b8f74c12419d1f", "lessThan": "caa8704a7f3cb7806331596195385437126ecb3a", "status": "affected", "versionType": "git" }, { "version": "2a437b86ac5a9893c902f30ef66815bf13587bf6", "lessThan": "a7c369e7da8203e2b5be12bbcac7b9ab2ed5b658", "status": "affected", "versionType": "git" }, { "version": "76c84c3728178b2d38d5604e399dfe8b0752645e", "lessThan": "a7eb6db1cd3f7b556a301dc1265945ad112089f7", "status": "affected", "versionType": "git" }, { "version": "cc55dd28c20a6611e30596019b3b2f636819a4c0", "lessThan": "834cbca3b12e46887f7a9b35f1981a888360ea4c", "status": "affected", "versionType": "git" }, { "version": "c2aba69d0c36a496ab4f2e81e9c2b271f2693fd7", "lessThan": "19b1994069dd29478ba767de1f98f14a088198dc", "status": "affected", "versionType": "git" }, { "version": "c2aba69d0c36a496ab4f2e81e9c2b271f2693fd7", "lessThan": "fc9f5ee1b073bd233d9c604e338af4ebb42cbc33", "status": "affected", "versionType": "git" }, { "version": "c2aba69d0c36a496ab4f2e81e9c2b271f2693fd7", "lessThan": "749179c2e25b95d22499ed29096b3e02d6dfd2b4", "status": "affected", "versionType": "git" }, { "version": "8f1c022541bf5a923c8d6fa483112c15250f30a4", "status": "affected", "versionType": "git" }, { "version": "c4e8a172501e677ebd8ea9d9161d97dc4df56fbd", "status": "affected", "versionType": "git" }, { "version": "5.10.238", "lessThan": "5.10.265", "status": "affected", "versionType": "semver" }, { "version": "5.15.185", "lessThan": "5.15.216", "status": "affected", "versionType": "semver" }, { "version": "6.1.141", "lessThan": "6.1.183", "status": "affected", "versionType": "semver" }, { "version": "6.6.93", "lessThan": "6.6.148", "status": "affected", "versionType": "semver" }, { "version": "6.12.31", "lessThan": "6.12.101", "status": "affected", "versionType": "semver" }, { "version": "5.4.294", "lessThan": "5.5", "status": "affected", "versionType": "semver" }, { "version": "6.14.9", "lessThan": "6.15", "status": "affected", "versionType": "semver" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/can/bcm.c" ], "versions": [ { "version": "6.15", "status": "affected" }, { "version": "0", "lessThan": "6.15", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.265", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.216", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.183", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.148", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.101", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.42", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1.5", "lessThanOrEqual": "7.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2", "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": "5.10.238", "versionEndExcluding": "5.10.265" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15.185", "versionEndExcluding": "5.15.216" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.1.141", "versionEndExcluding": "6.1.183" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.6.93", "versionEndExcluding": "6.6.148" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.12.31", "versionEndExcluding": "6.12.101" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.15", "versionEndExcluding": "6.18.42" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.15", "versionEndExcluding": "7.1.5" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.15", "versionEndExcluding": "7.2" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.4.294" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.14.9" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/96994180bd7b248b0cc698afe926e23fc1bda59b" }, { "url": "https://git.kernel.org/stable/c/caa8704a7f3cb7806331596195385437126ecb3a" }, { "url": "https://git.kernel.org/stable/c/a7c369e7da8203e2b5be12bbcac7b9ab2ed5b658" }, { "url": "https://git.kernel.org/stable/c/a7eb6db1cd3f7b556a301dc1265945ad112089f7" }, { "url": "https://git.kernel.org/stable/c/834cbca3b12e46887f7a9b35f1981a888360ea4c" }, { "url": "https://git.kernel.org/stable/c/19b1994069dd29478ba767de1f98f14a088198dc" }, { "url": "https://git.kernel.org/stable/c/fc9f5ee1b073bd233d9c604e338af4ebb42cbc33" }, { "url": "https://git.kernel.org/stable/c/749179c2e25b95d22499ed29096b3e02d6dfd2b4" } ], "title": "can: bcm: add locking when updating filter and timer values", "x_generator": { "engine": "bippy-1.2.0" } } } }