{"id":"CVE-2026-72122","state":"PUBLISHED","title":"can: bcm: fix lockless bound/ifindex race and silent RX_SETUP failure","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ncan: bcm: fix lockless bound/ifindex race and silent RX_SETUP failure\n\nbcm_sendmsg() reads bo->ifindex and checks bo->bound before taking\nlock_sock(), while bcm_notify(), bcm_connect() and bcm_release() all\nmutate both fields under that same lock. Because the lockless reads\nand the locked writes are unordered with respect to each other, a\nracing bcm_notify() (device unregister) or bcm_connect() (concurrent\nbind on another thread sharing the socket) can make bcm_sendmsg()\nobserve an inconsistent combination, e.g. a stale bound=1 together\nwith the now-cleared ifindex=0, silently turning a socket bound to a\nspecific CAN interface into one that also matches \"any\" interface.\n\nKeep the lockless bo->bound check purely as a fast-path reject, and\nmove the ifindex read (and a bo->bound re-check) into the locked\nsection, where every writer already serializes. This removes the\npossibility of observing the two fields torn against each other,\nrather than trying to fix it with more READ_ONCE()/WRITE_ONCE() pairs\non two independently updated fields. Annotate the now-purely-lockless\nbo->bound accesses consistently across all its write sites.\n\nAlso fix bcm_rx_setup() silently returning success when the target\ndevice disappears concurrently instead of reporting -ENODEV, so a\nbroken RX op is no longer left registered as if it had succeeded.","publishedAt":"2026-08-15T05:53:00.704Z","updatedAt":"2026-10-16T18:44:57.450Z","severity":{"score":7.3,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:L","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"ffd980f976e7fd666c2e61bf8ab35107efd11828","status":"affected","lessThan":"9e60c586faeaed80d55ab8ce2a4b8e56133bc395","versionType":"git"},{"version":"ffd980f976e7fd666c2e61bf8ab35107efd11828","status":"affected","lessThan":"ffa80a2af27c97453861a5128e537214a31cd18a","versionType":"git"},{"version":"ffd980f976e7fd666c2e61bf8ab35107efd11828","status":"affected","lessThan":"6bcc5cd247c2934373bc2a1cdf8bf12321169543","versionType":"git"},{"version":"ffd980f976e7fd666c2e61bf8ab35107efd11828","status":"affected","lessThan":"0f6f9f95294b4cbb26ba02209e893e3bd91237c3","versionType":"git"},{"version":"ffd980f976e7fd666c2e61bf8ab35107efd11828","status":"affected","lessThan":"b70f1a15533afeeec5d07f20bec3f3867ab1c7b6","versionType":"git"},{"version":"ffd980f976e7fd666c2e61bf8ab35107efd11828","status":"affected","lessThan":"35f0ac19efb1a3f6c5e12c00e475a9ec2d9c3a6d","versionType":"git"},{"version":"ffd980f976e7fd666c2e61bf8ab35107efd11828","status":"affected","lessThan":"b9c6ac6fb4e01b34575816066e5d3890a57b3c86","versionType":"git"},{"version":"ffd980f976e7fd666c2e61bf8ab35107efd11828","status":"affected","lessThan":"d9b091d9d22fee81ec53fb55d2032951993ceadb","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/can/bcm.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.25","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.25","versionType":"semver"},{"version":"5.10.261","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.212","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.178","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.145","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.97","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.40","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.5","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/can/bcm.c"]}],"references":["https://git.kernel.org/stable/c/9e60c586faeaed80d55ab8ce2a4b8e56133bc395","https://git.kernel.org/stable/c/ffa80a2af27c97453861a5128e537214a31cd18a","https://git.kernel.org/stable/c/6bcc5cd247c2934373bc2a1cdf8bf12321169543","https://git.kernel.org/stable/c/0f6f9f95294b4cbb26ba02209e893e3bd91237c3","https://git.kernel.org/stable/c/b70f1a15533afeeec5d07f20bec3f3867ab1c7b6","https://git.kernel.org/stable/c/35f0ac19efb1a3f6c5e12c00e475a9ec2d9c3a6d","https://git.kernel.org/stable/c/b9c6ac6fb4e01b34575816066e5d3890a57b3c86","https://git.kernel.org/stable/c/d9b091d9d22fee81ec53fb55d2032951993ceadb"],"weaknesses":[],"ingestedAt":"2026-10-29T20:12:58.252Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/72xxx/CVE-2026-72122.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-72122","state":"PUBLISHED","datePublished":"2026-08-15T05:53:00.704Z","dateUpdated":"2026-10-16T18:44:57.450Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-08-09T03:40:39.907Z"},"containers":{"cna":{"title":"can: bcm: fix lockless bound/ifindex race and silent RX_SETUP failure","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\ncan: bcm: fix lockless bound/ifindex race and silent RX_SETUP failure\n\nbcm_sendmsg() reads bo->ifindex and checks bo->bound before taking\nlock_sock(), while bcm_notify(), bcm_connect() and bcm_release() all\nmutate both fields under that same lock. Because the lockless reads\nand the locked writes are unordered with respect to each other, a\nracing bcm_notify() (device unregister) or bcm_connect() (concurrent\nbind on another thread sharing the socket) can make bcm_sendmsg()\nobserve an inconsistent combination, e.g. a stale bound=1 together\nwith the now-cleared ifindex=0, silently turning a socket bound to a\nspecific CAN interface into one that also matches \"any\" interface.\n\nKeep the lockless bo->bound check purely as a fast-path reject, and\nmove the ifindex read (and a bo->bound re-check) into the locked\nsection, where every writer already serializes. This removes the\npossibility of observing the two fields torn against each other,\nrather than trying to fix it with more READ_ONCE()/WRITE_ONCE() pairs\non two independently updated fields. Annotate the now-purely-lockless\nbo->bound accesses consistently across all its write sites.\n\nAlso fix bcm_rx_setup() silently returning success when the target\ndevice disappears concurrently instead of reporting -ENODEV, so a\nbroken RX op is no longer left registered as if it had succeeded."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"ffd980f976e7fd666c2e61bf8ab35107efd11828","status":"affected","lessThan":"9e60c586faeaed80d55ab8ce2a4b8e56133bc395","versionType":"git"},{"version":"ffd980f976e7fd666c2e61bf8ab35107efd11828","status":"affected","lessThan":"ffa80a2af27c97453861a5128e537214a31cd18a","versionType":"git"},{"version":"ffd980f976e7fd666c2e61bf8ab35107efd11828","status":"affected","lessThan":"6bcc5cd247c2934373bc2a1cdf8bf12321169543","versionType":"git"},{"version":"ffd980f976e7fd666c2e61bf8ab35107efd11828","status":"affected","lessThan":"0f6f9f95294b4cbb26ba02209e893e3bd91237c3","versionType":"git"},{"version":"ffd980f976e7fd666c2e61bf8ab35107efd11828","status":"affected","lessThan":"b70f1a15533afeeec5d07f20bec3f3867ab1c7b6","versionType":"git"},{"version":"ffd980f976e7fd666c2e61bf8ab35107efd11828","status":"affected","lessThan":"35f0ac19efb1a3f6c5e12c00e475a9ec2d9c3a6d","versionType":"git"},{"version":"ffd980f976e7fd666c2e61bf8ab35107efd11828","status":"affected","lessThan":"b9c6ac6fb4e01b34575816066e5d3890a57b3c86","versionType":"git"},{"version":"ffd980f976e7fd666c2e61bf8ab35107efd11828","status":"affected","lessThan":"d9b091d9d22fee81ec53fb55d2032951993ceadb","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/can/bcm.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.25","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.25","versionType":"semver"},{"version":"5.10.261","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.212","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.178","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.145","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.97","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.40","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.5","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/can/bcm.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/9e60c586faeaed80d55ab8ce2a4b8e56133bc395"},{"url":"https://git.kernel.org/stable/c/ffa80a2af27c97453861a5128e537214a31cd18a"},{"url":"https://git.kernel.org/stable/c/6bcc5cd247c2934373bc2a1cdf8bf12321169543"},{"url":"https://git.kernel.org/stable/c/0f6f9f95294b4cbb26ba02209e893e3bd91237c3"},{"url":"https://git.kernel.org/stable/c/b70f1a15533afeeec5d07f20bec3f3867ab1c7b6"},{"url":"https://git.kernel.org/stable/c/35f0ac19efb1a3f6c5e12c00e475a9ec2d9c3a6d"},{"url":"https://git.kernel.org/stable/c/b9c6ac6fb4e01b34575816066e5d3890a57b3c86"},{"url":"https://git.kernel.org/stable/c/d9b091d9d22fee81ec53fb55d2032951993ceadb"}],"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:L","baseScore":7.3,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - Exploitation requires local access to a PF_CAN SOCK_DGRAM CAN_BCM socket via sendmsg()/connect() syscalls; the race is in kernel socket state handling, not in remote packet reception or the physical CAN bus itself.\nAC:L - The attacker controls both sides of the race by concurrently calling sendmsg() on one thread while triggering bcm_connect() or NETDEV_UNREGISTER (e.g. ip link del) on another, making the torn bound/ifindex observation reliably triggerable.\nPR:L - No real-root capability is required beyond opening BCM sockets and binding to a CAN interface; unprivileged users with CAN access or CAP_NET_ADMIN via user namespaces can create vcan devices and drive the unregister/connect race.\nUI:N - Exploitation is fully attacker-driven through concurrent syscalls and does not require any victim user action such as mounting filesystems or opening files.\nS:U - The impact is unauthorized access to additional CAN interfaces within the same kernel security domain, not a cross-boundary escape such as VM breakout, sandbox escape, or IOMMU bypass.\nC:H - Racing to observe bound=1 with ifindex=0 causes RX_SETUP to register can_rx_register() on all CAN devices, letting a socket bound to one interface sniff traffic from every other CAN bus on the system including safety-critical vehicle or industrial networks.\nI:H - The same torn state enables TX_SETUP/TX_SEND on arbitrary interfaces via msg_name when per-socket binding would normally block it, allowing injection of attacker-controlled CAN frames onto buses the process was not authorized to transmit on.\nA:L - The concurrent bcm_rx_setup() bug can silently return success without registering a filter when the target device vanishes, degrading CAN monitoring reliability without causing kernel panic, oops, or deadlock."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-17T05:40:35.588Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.25","versionEndExcluding":"5.10.261"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.25","versionEndExcluding":"5.15.212"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.25","versionEndExcluding":"6.1.178"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.25","versionEndExcluding":"6.6.145"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.25","versionEndExcluding":"6.12.97"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.25","versionEndExcluding":"6.18.40"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.25","versionEndExcluding":"7.1.5"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.25","versionEndExcluding":"7.2"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-72122","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"version":"2.0.3","timestamp":"2026-10-16T18:42:08.458786Z"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-16T18:44:57.450Z"}}]}}}