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CVE-2026-17523 (GCVE-0-2026-17523)

Vulnerability from cvelistv5 – Published: 2026-07-27 08:58 – Updated: 2026-09-10 13:31
VLAI
Title
can: bcm: switch timer to HRTIMER_MODE_SOFT and remove hrtimer_tasklet
Summary
In the Linux kernel, the following vulnerability has been resolved: can: bcm: switch timer to HRTIMER_MODE_SOFT and remove hrtimer_tasklet This patch switches the timer to HRTIMER_MODE_SOFT, which executed the timer callback in softirq context and removes the hrtimer_tasklet.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
SSVC
Exploitation: none Automatable: no Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-07-27 13:44 UTC
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: c53a6ee88b0a91bd012ef1b7988c0b93dae6f24d , < 79305a826f872fe446c6fbf8450f515053ef6951 (git)
Affected: c53a6ee88b0a91bd012ef1b7988c0b93dae6f24d , < bf74aa86e111aa3b2fbb25db37e3a3fab71b5b68 (git)
guessed Create a notification for this product.
Linux Linux Affected: 2.6.29
Unaffected: 0 , < 2.6.29 (semver)
Unaffected: 4.19.226 , ≤ 4.19.* (semver)
Unaffected: 5.4 , ≤ * (original_commit_for_fix)
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Show details on NVD website
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              "value": "AV:L - The UAF is in bcm_remove_op() hrtimer/tasklet teardown, reached only via local PF_CAN/CAN_BCM syscalls (socket/connect/sendmsg TX_SETUP or RX_SETUP with STARTTIMER, then close or TX_DELETE/RX_DELETE). 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."
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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


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