CVE-2026-90309 RDMA/erdma: Hold CQ references when processing EQ events
A use-after-free vulnerability in the Linux kernel's erdma driver allows attackers to cause denial of service or execute code via race conditions during CQ destruction.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-90309?
CVE-2026-90309 is a high-severity use after free vulnerability in Linux, published on 17 Sep 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:
RDMA/erdma: Hold CQ references when processing EQ events
EQ handlers look up CQs from dev->cq_xa and invoke CQ completion or error callbacks outside the xarray lock. erdma_destroy_cq() can erase the CQ from the xarray and free its queue buffer and doorbell record while a previously scheduled EQ handler is still using the CQ.
Add a CQ refcount and take a reference under the xarray lock with refcount_inc_not_zero(). Remove the CQ from the xarray before dropping the destroy-path reference, then wait for in-flight EQ users before releasing CQ resources.
Which versions are affected by CVE-2026-90309?
How do I fix CVE-2026-90309?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-90309 being exploited?
There is no known exploitation of CVE-2026-90309 in the wild and no public exploit code.
Sources
Also known as AZL-102878, BELL-CVE-2026-90309, DEBIAN-CVE-2026-90309, GHSA-p9h2-4fgm-97q7, UBUNTU-CVE-2026-90309.