CVE-2026-98347 IB/IPoIB: Avoid restoring OPER_UP after multicast flush
A race condition in the Linux kernel IPoIB driver can cause a deadlock during interface shutdown, leading to a denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-98347?
CVE-2026-98347 is a vulnerability in Linux, published on 6 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
IB/IPoIB: Avoid restoring OPER_UP after multicast flush
ipoib_ib_dev_flush_light() temporarily clears IPOIB_FLAG_OPER_UP to prevent multicast joins while ipoib_mcast_dev_flush() is running, and restores the flag afterwards if it was previously set.
This restore races with ipoib_ib_dev_down(). If the interface is brought down while the flush is in progress, ipoib_ib_dev_down() clears IPOIB_FLAG_OPER_UP, but the flush path may set it again after the device has already gone down.
Since commit 894021a75291 ("IB/ipoib: Make the carrier_on_task race aware"), ipoib_mcast_carrier_on_task() relies on IPOIB_FLAG_OPER_UP being cleared to terminate its rtnl_trylock() retry loop. If the flag is left set after shutdown, the workqueue retries forever, causing teardown to deadlock when ipoib_ndo_uninit() waits in destroy_workqueue() while holding RTNL.
Instead of overloading IPOIB_FLAG_OPER_UP to block multicast joins during a light flush, introduce a dedicated IPOIB_FLAG_MCAST_FLUSH flag. Use it together with IPOIB_FLAG_OPER_UP to determine whether multicast joins are allowed, avoiding the race with device shutdown.
Which versions are affected by CVE-2026-98347?
How do I fix CVE-2026-98347?
Apply the vendor's patch.
Is CVE-2026-98347 being exploited?
There is no known exploitation of CVE-2026-98347 in the wild and no public exploit code.
Sources
Also known as AZL-106446, BELL-CVE-2026-98347, DEBIAN-CVE-2026-98347, GHSA-8j4r-887v-cjjx, UBUNTU-CVE-2026-98347.