CVE-2026-72125: can: isotp: fix use-after-free race with concurrent NETDEV_UNREGISTER
In the Linux kernel, the following vulnerability has been resolved:
can: isotp: fix use-after-free race with concurrent NETDEVUNREGISTER
isotprelease() looked up the bound network device via devgetbyindex() using the stored ifindex. During device unregistration the device is unlisted from the ifindex hash before the NETDEVUNREGISTER notifier chain runs, so a concurrent isotprelease() could find no device, skip canrxunregister() entirely, and still proceed to free the socket. Since isotprelease() had already removed itself from the isotp notifier list at that point, isotpnotify() would never get a chance to clean up either, leaving a stale CAN filter that keeps pointing at the freed socket.
Fix this the same way raw.c already does: hold a tracked reference to the bound netdevice in the socket (so->dev/so->devtracker) from bind() onward instead of re-resolving it from the ifindex, and serialize bind()/release() with rtnllock() so that so->dev is always consistent with what the NETDEVUNREGISTER notifier sees. so->dev stays valid regardless of ifindex-hash unlisting, and is only ever cleared by whichever of isotprelease()/isotpnotify() gets there first, so the filter is always removed exactly once.
isotpbind() now rejects a (re)bind with -EAGAIN while so->[tx|rx].state isn't ISOTPIDLE yet, so a timer left running by a prior NETDEVUNREGISTER can't act on a newly bound so->ifindex. Both checks share the same locksock() section, so there is no window in which a concurrent isotpnotify() clearing so->bound could be missed.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
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ubuntu/linuxto a version that resolves this vulnerability.Fixed in 7.0.0-38.38 - Upgrade
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ubuntu/linux-riscvto a version that resolves this vulnerability.Fixed in 7.0.0-38.38.1 - Compensating control
Modify CAN ISOTP socket handling so bind() stores a tracked reference to the bound net_device in so->dev/so->dev_tracker instead of re-resolving it from the ifindex; serialize bind() and release() with rtnl_lock(); and reject a rebind with -EAGAIN while so->tx.state or so->rx.state is not ISOTP_IDLE.
Event History
Frequently Asked Questions
What is the severity of CVE-2026-72125?
CVE-2026-72125 has a risk score of 44, indicating a moderate level of severity.
How do I fix CVE-2026-72125?
To fix CVE-2026-72125, ensure you update your Linux kernel to the patched version that addresses the use-after-free vulnerability.
What type of vulnerability is CVE-2026-72125?
CVE-2026-72125 is classified as a Use After Free vulnerability in the Linux kernel.
What is affected by CVE-2026-72125?
CVE-2026-72125 affects the Linux kernel's CAN ISOTP implementation related to network device management.
When was CVE-2026-72125 published?
CVE-2026-72125 was published on August 15, 2026.