CVE-2026-89506 RDMA/uverbs: Add UVERBS_ATTR_UHW to UVERBS_METHOD_REG_MR
A malicious local user can trigger a kernel crash in RDMA drivers by passing invalid user hardware data, causing a denial of service.
- 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-2026-89506?
CVE-2026-89506 is a vulnerability in Linux, published on 11 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/uverbs: Add UVERBS_ATTR_UHW to UVERBS_METHOD_REG_MR
The original commit missed that three drivers (mthca, irdma, siw) have UHW data associated with reg_mr that cannot be passed through the ioctl. They also assume that the udata cannot be NULL, so failing to pass a valid udata can trigger a NULL udata crash in those drivers.
This never happens in real systems since in rdma-core ibv_cmd_reg_mr_ex() does not accept a udata and those three drivers don't use it, however a malicious userspace could trigger it.
Which versions are affected by CVE-2026-89506?
How do I fix CVE-2026-89506?
Apply the vendor's patch.
Is CVE-2026-89506 being exploited?
There is no known exploitation of CVE-2026-89506 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-89506, DEBIAN-CVE-2026-89506, GHSA-pfq2-9rm7-2x65, UBUNTU-CVE-2026-89506.