CVE-2026-17523

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Remote IP services or CAN bus frames alone cannot close the socket or delete the op.\nAC:L - The attacker controls both sides of the race: they arm cyclic TX/RX hrtimers with attacker-chosen microsecond intervals, then delete the op or close the socket, hitting the TOCTOU between tasklet-state checks and hrtimer_active() in bcm_remove_op(). The window is retryable until the scheduled tasklet runs on the freed object.\nPR:L - can_create(), bcm_connect(), and bcm_sendmsg() have no capability checks. RX_SETUP with ifindex 0 starts timeout timers without a CAN device, so any unprivileged local user (including via user namespaces / vcan) can create BCM ops and trigger teardown.\nUI:N - Exploitation requires only the attacker opening a BCM socket, installing timer-armed TX_SETUP/RX_SETUP ops, and closing or deleting them; no victim action such as mounting a filesystem or opening a file is needed.\nS:U - The use-after-free corrupts kernel heap state in the same kernel security domain, enabling local privilege escalation or crash; it does not by itself cross a VM, guest-to-host, or IOMMU boundary.\nC:H - bcm_op is a kmalloc object that embeds tasklet_struct; after the hrtimer hardirq callback schedules a tasklet that bcm_remove_op() misses, the tasklet runs on freed memory. Heap reuse of tsklet.func/data and UAF reads in bcm_send_to_user()/bcm_can_tx() enable arbitrary kernel disclosure.\nI:H - The same UAF lets a sprayed tasklet_struct hijack tsklet.func for arbitrary kernel execution, and bcm_tx_timeout_tsklet()/bcm_can_tx() write through freed op fields (frames, sock, timers), providing arbitrary write and control-flow hijack primitives.\nA:H - A scheduled tasklet running after kfree(op) dereferences the freed bcm_op (and its frames/sk pointers), causing kernel oops/panic even when the UAF is not fully turned into code execution."}]}], "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": "c53a6ee88b0a91bd012ef1b7988c0b93dae6f24d", "lessThan": "79305a826f872fe446c6fbf8450f515053ef6951", "status": "affected", "versionType": "git"}, {"version": "c53a6ee88b0a91bd012ef1b7988c0b93dae6f24d", "lessThan": "bf74aa86e111aa3b2fbb25db37e3a3fab71b5b68", "status": "affected", "versionType": "git"}]}, {"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": "2.6.29", "status": "affected"}, {"version": "0", "lessThan": "2.6.29", "status": "unaffected", "versionType": "semver"}, {"version": "4.19.226", "lessThanOrEqual": "4.19.*", "status": "unaffected", "versionType": "semver"}, {"version": "5.4", "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": "2.6.29", "versionEndExcluding": "4.19.226"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.29", "versionEndExcluding": "5.4"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/79305a826f872fe446c6fbf8450f515053ef6951"}, {"url": "https://git.kernel.org/stable/c/bf74aa86e111aa3b2fbb25db37e3a3fab71b5b68"}], "title": "can: bcm: switch timer to HRTIMER_MODE_SOFT and remove hrtimer_tasklet", "x_generator": {"engine": "bippy-1.2.0"}}, "adp": [{"metrics": [{"other": {"type": "ssvc", "content": {"timestamp": "2026-07-27T13:44:24.567768Z", "id": "CVE-2026-17523", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "total"}], "role": "CISA Coordinator", "version": "2.0.3"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-07-27T13:44:45.277Z"}}]}}

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