High [CVE-2026-72126] use unconditional synchronize_rcu in isotp_release
This high-severity Red Hat Linux advisory covers CVE-2026-72126 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat package: kernel-rt.
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Summary
In the Linux kernel, the following vulnerability has been resolved: can: isotp: use unconditional synchronize_rcu() in isotp_release() isotp_notify() unregisters the (RCU) CAN filters via can_rx_unregister() and clears so->bound without waiting for a grace period. isotp_release() uses so->bound to decide whether it needs to call synchronize_rcu() before cancelling so->rxtimer, so when NETDEV_UNREGISTER runs first it skips that synchronize_rcu() and can cancel the timer while an in-flight isotp_rcv() is still executing and about to re-arm it via isotp_send_fc(), leading to a use-after-free timer callback on the freed socket. sakisho-bot remarked a problem with rtnl_lock held in isotp_notify(), therefore make isotp_release() always call synchronize_rcu() before cancelling the timers, regardless of so->bound.
This still closes the original race (isotp_notify() clearing so->bound without waiting for in-flight isotp_rcv() callers before isotp_release() cancels the RX timer) without adding any RCU wait to the netdevice notifier path. A flaw was found in the Linux kernel's Controller Area Network (CAN) ISO-TP (isotp) module.
This vulnerability arises from a race condition where the `isotp_release()` function can cancel a timer while it is still actively being used by `isotp_rcv()`.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · medium-confidence parse· fetched 23 days ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · medium-confidence parse· fetched 23 days ago·verify at source
Mitigation
The source record does not include mitigation steps. That is not a statement that no fix exists — read the vendor advisory below for the authoritative guidance.
Official advisory · medium-confidence parse· fetched 23 days ago·verify at source
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