CVE-2026-43163 md/bitmap: fix GPF in write_page caused by resize race
A race condition in the Linux kernel's md/bitmap module causes a General Protection Fault during array resize, leading to 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-2026-43163?
CVE-2026-43163 is a medium-severity 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:
md/bitmap: fix GPF in write_page caused by resize race
A General Protection Fault occurs in write_page() during array resize: RIP: 0010:write_page+0x22b/0x3c0 [md_mod]
This is a use-after-free race between bitmap_daemon_work() and __bitmap_resize(). The daemon iterates over `bitmap->storage.filemap` without locking, while the resize path frees that storage via md_bitmap_file_unmap(). `quiesce()` does not stop the md thread, allowing concurrent access to freed pages.
Fix by holding `mddev->bitmap_info.mutex` during the bitmap update.
Weakness: CWE-362
Which versions are affected by CVE-2026-43163?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-43163?
Apply the vendor's patch.
Is CVE-2026-43163 being exploited?
There is no known exploitation of CVE-2026-43163 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-43163, DEBIAN-CVE-2026-43163, GHSA-4hfr-m4m2-94ff, ROOT-OS-DEBIAN-11-CVE-2026-43163, ROOT-OS-UBUNTU-2204-CVE-2026-43163, ROOT-OS-UBUNTU-2404-CVE-2026-43163 and 1 more.