CVE-2026-43120 RDMA/irdma: Fix double free related to rereg_user_mr

High 7.8 Published 6 May 2026 Updated 19 Oct 2026

A double free vulnerability in the Linux kernel's irdma RDMA driver allows attackers to cause denial of service or potentially execute code via memory corruption.

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-2026-43120?

CVE-2026-43120 is a high-severity use after free vulnerability in Linux kernel, published on 6 May 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/irdma: Fix double free related to rereg_user_mr

If IB_MR_REREG_TRANS is set during rereg_user_mr, the umem will be released and a new one will be allocated in irdma_rereg_mr_trans. If any step of irdma_rereg_mr_trans fails after the new umem is allocated, it releases the umem, but does not set iwmr->region to NULL. The problem is that this failure is propagated to the user, who will then call ibv_dereg_mr (as they should). Then, the dereg_mr path will see a non-NULL umem and attempt to call ib_umem_release again.

Fix this by setting iwmr->region to NULL after ib_umem_release.

Fixed: 5ac388db27c4 ("RDMA/irdma: Add support to re-register a memory region")

Weakness: CWE-415

Which versions are affected by CVE-2026-43120?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2026-43120?

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-2026-43120 being exploited?

There is no known exploitation of CVE-2026-43120 in the wild and no public exploit code.

All Linux kernel vulnerabilities

Sources

Also known as BELL-CVE-2026-43120, DEBIAN-CVE-2026-43120, GHSA-74jp-62v9-rvjf, ROOT-OS-DEBIAN-11-CVE-2026-43120, ROOT-OS-DEBIAN-12-CVE-2026-43120, ROOT-OS-UBUNTU-2204-CVE-2026-43120 and 2 more.