{"answers":{"affected":"","exploited":"There is no known exploitation of CVE-2026-72121 in the wild and no public exploit code.","fix":"Apply the vendor's patch.","what":"CVE-2026-72121 is a high-severity vulnerability in Linux, published on 15 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim."},"fix_prompt":"Check this codebase for CVE-2026-72121 and fix it if it is affected.\n\nWhat it is: CVE-2026-72121 is a high-severity vulnerability in Linux, published on 15 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.\nExploitation: There is no known exploitation of CVE-2026-72121 in the wild and no public exploit code.\n\nAffected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.\n\nTask:\n1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.\n2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.\n3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.\n4. Run the tests and summarise what changed and why.\n5. If nothing in the project is affected, say so and change nothing.\n\nReference: https://insights.sbomify.com/CVE-2026-72121/ (Markdown: https://insights.sbomify.com/CVE-2026-72121/index.md)","id":"CVE-2026-72121","markdown":"https://insights.sbomify.com/CVE-2026-72121/index.md","name":"CVE-2026-72121","record":{"aliases":["BELL-CVE-2026-72121","DEBIAN-CVE-2026-72121","GHSA-85wx-h4w2-c465","UBUNTU-CVE-2026-72121"],"analysis":{"component_type":"kernel","fix_type":"patch","impacts":["other"],"network_reachable":"adjacent_or_local","non_default_config":false,"product_category":"Linux kernel CAN BCM","requires_auth":"none","summary":"A race condition in the Linux kernel CAN BCM module allows concurrent access to timer and filter values, potentially causing inconsistent state or stale transmissions.","user_interaction":"not_required","vuln_class":"race_condition"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"Linux","cpe":[],"cvss":{"score":8.8,"severity":"high","source":"cna","vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","version":"3.1"},"cwes":[],"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-\u003eframes 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-\u003eflags 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-\u003ecurrframe 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.","ecosystems":[],"exploits":{"exploitdb":0,"first_seen":null,"github_poc":0,"max_poc_stars":null,"metasploit":0,"nuclei":0,"refs":[],"tier":"none_known"},"has_fix":true,"headline":"can: bcm: add locking when updating filter and timer values","id":"CVE-2026-72121","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":null,"products":[],"type":"race_condition","year":"2026"},"n_packages":0,"n_references":8,"next":{"headline":"can: bcm: fix lockless bound/ifindex race and silent RX_SETUP failure","id":"CVE-2026-72122"},"packages":[],"prev":{"headline":"can: bcm: add missing rcu list annotations and operations","id":"CVE-2026-72120"},"products":["Linux"],"published":"2026-08-15","related":[],"sources":[{"class":"attribution","licence":"CVE Terms of Use (MITRE)","name":"CVE List","prefix":"CVE"},{"class":"attribution","licence":"FIRST CVSS licence","name":"CVSS (FIRST)"}],"ssvc":{"automatable":"no","exploitation":"none","technical_impact":"total"},"state":"PUBLISHED","updated":"2026-10-16","vendors":["Linux"]},"summary":"A race condition in the Linux kernel CAN BCM module allows concurrent access to timer and filter values, potentially causing inconsistent state or stale transmissions.","url":"https://insights.sbomify.com/CVE-2026-72121/"}