{"api_version":"1","generated_at":"2026-09-11T17:12:15+00:00","cve":"CVE-2026-72121","urls":{"html":"https://cve.report/CVE-2026-72121","api":"https://cve.report/api/cve/CVE-2026-72121.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-72121","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-72121"},"summary":{"title":"can: bcm: add locking when updating filter and timer values","description":"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.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-08-15 06:21:26","updated_at":"2026-08-19 17:20:59"},"problem_types":[],"metrics":[{"version":"3.1","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","score":"8.8","severity":"HIGH","vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","data":{"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","attackVector":"ADJACENT_NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"}},{"version":"3.1","source":"CNA","type":"DECLARED","score":"8.8","severity":"HIGH","vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","data":{"baseScore":8.8,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","version":"3.1"}}],"references":[{"url":"https://git.kernel.org/stable/c/a7c369e7da8203e2b5be12bbcac7b9ab2ed5b658","name":"https://git.kernel.org/stable/c/a7c369e7da8203e2b5be12bbcac7b9ab2ed5b658","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/749179c2e25b95d22499ed29096b3e02d6dfd2b4","name":"https://git.kernel.org/stable/c/749179c2e25b95d22499ed29096b3e02d6dfd2b4","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/a7eb6db1cd3f7b556a301dc1265945ad112089f7","name":"https://git.kernel.org/stable/c/a7eb6db1cd3f7b556a301dc1265945ad112089f7","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/fc9f5ee1b073bd233d9c604e338af4ebb42cbc33","name":"https://git.kernel.org/stable/c/fc9f5ee1b073bd233d9c604e338af4ebb42cbc33","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/96994180bd7b248b0cc698afe926e23fc1bda59b","name":"https://git.kernel.org/stable/c/96994180bd7b248b0cc698afe926e23fc1bda59b","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/caa8704a7f3cb7806331596195385437126ecb3a","name":"https://git.kernel.org/stable/c/caa8704a7f3cb7806331596195385437126ecb3a","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/834cbca3b12e46887f7a9b35f1981a888360ea4c","name":"https://git.kernel.org/stable/c/834cbca3b12e46887f7a9b35f1981a888360ea4c","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/19b1994069dd29478ba767de1f98f14a088198dc","name":"https://git.kernel.org/stable/c/19b1994069dd29478ba767de1f98f14a088198dc","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-72121","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-72121","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 7595de7bc56e0e52b74e56c90f7e247bf626d628 96994180bd7b248b0cc698afe926e23fc1bda59b git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected fbd8fdc2b218e979cfe422b139b8f74c12419d1f caa8704a7f3cb7806331596195385437126ecb3a git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 2a437b86ac5a9893c902f30ef66815bf13587bf6 a7c369e7da8203e2b5be12bbcac7b9ab2ed5b658 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 76c84c3728178b2d38d5604e399dfe8b0752645e a7eb6db1cd3f7b556a301dc1265945ad112089f7 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 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original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"72121","cve":"CVE-2026-72121","epss":"0.003330000","percentile":"0.263530000","score_date":"2026-08-19","updated_at":"2026-08-20 00:13:09"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["net/can/bcm.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"96994180bd7b248b0cc698afe926e23fc1bda59b","status":"affected","version":"7595de7bc56e0e52b74e56c90f7e247bf626d628","versionType":"git"},{"lessThan":"caa8704a7f3cb7806331596195385437126ecb3a","status":"affected","version":"fbd8fdc2b218e979cfe422b139b8f74c12419d1f","versionType":"git"},{"lessThan":"a7c369e7da8203e2b5be12bbcac7b9ab2ed5b658","status":"affected","version":"2a437b86ac5a9893c902f30ef66815bf13587bf6","versionType":"git"},{"lessThan":"a7eb6db1cd3f7b556a301dc1265945ad112089f7","status":"affected","version":"76c84c3728178b2d38d5604e399dfe8b0752645e","versionType":"git"},{"lessThan":"834cbca3b12e46887f7a9b35f1981a888360ea4c","status":"affected","version":"cc55dd28c20a6611e30596019b3b2f636819a4c0","versionType":"git"},{"lessThan":"19b1994069dd29478ba767de1f98f14a088198dc","status":"affected","version":"c2aba69d0c36a496ab4f2e81e9c2b271f2693fd7","versionType":"git"},{"lessThan":"fc9f5ee1b073bd233d9c604e338af4ebb42cbc33","status":"affected","version":"c2aba69d0c36a496ab4f2e81e9c2b271f2693fd7","versionType":"git"},{"lessThan":"749179c2e25b95d22499ed29096b3e02d6dfd2b4","status":"affected","version":"c2aba69d0c36a496ab4f2e81e9c2b271f2693fd7","versionType":"git"},{"status":"affected","version":"8f1c022541bf5a923c8d6fa483112c15250f30a4","versionType":"git"},{"status":"affected","version":"c4e8a172501e677ebd8ea9d9161d97dc4df56fbd","versionType":"git"},{"lessThan":"5.10.265","status":"affected","version":"5.10.238","versionType":"semver"},{"lessThan":"5.15.216","status":"affected","version":"5.15.185","versionType":"semver"},{"lessThan":"6.1.183","status":"affected","version":"6.1.141","versionType":"semver"},{"lessThan":"6.6.148","status":"affected","version":"6.6.93","versionType":"semver"},{"lessThan":"6.12.101","status":"affected","version":"6.12.31","versionType":"semver"},{"lessThan":"5.5","status":"affected","version":"5.4.294","versionType":"semver"},{"lessThan":"6.15","status":"affected","version":"6.14.9","versionType":"semver"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["net/can/bcm.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"6.15"},{"lessThan":"6.15","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"5.10.*","status":"unaffected","version":"5.10.265","versionType":"semver"},{"lessThanOrEqual":"5.15.*","status":"unaffected","version":"5.15.216","versionType":"semver"},{"lessThanOrEqual":"6.1.*","status":"unaffected","version":"6.1.183","versionType":"semver"},{"lessThanOrEqual":"6.6.*","status":"unaffected","version":"6.6.148","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.101","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.42","versionType":"semver"},{"lessThanOrEqual":"7.1.*","status":"unaffected","version":"7.1.5","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.2","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"5.10.265","versionStartIncluding":"5.10.238","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"5.15.216","versionStartIncluding":"5.15.185","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.1.183","versionStartIncluding":"6.1.141","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.6.148","versionStartIncluding":"6.6.93","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.101","versionStartIncluding":"6.12.31","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.42","versionStartIncluding":"6.15","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.1.5","versionStartIncluding":"6.15","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2","versionStartIncluding":"6.15","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","vulnerable":true}],"negate":false,"operator":"OR"}]}],"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":{"baseScore":8.8,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","version":"3.1"},"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."}]}],"providerMetadata":{"dateUpdated":"2026-08-19T16:36:16.520Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"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"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-72121","datePublished":"2026-08-15T05:52:59.959Z","dateReserved":"2026-08-09T03:40:39.907Z","dateUpdated":"2026-08-19T16:36:16.520Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-08-15 06:21:26","lastModifiedDate":"2026-08-19 17:20:59","problem_types":[],"metrics":{"cvssMetricV31":[{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","cvssData":{"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","attackVector":"ADJACENT_NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":2.8,"impactScore":5.9}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"72121","Ordinal":"1","Title":"can: bcm: add locking when updating filter and timer values","CVE":"CVE-2026-72121","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"72121","Ordinal":"1","NoteData":"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.","Type":"Description","Title":"can: bcm: add locking when updating filter and timer values"}]}}}