CVE-2026-31447 ext4: reject mount if bigalloc with s_first_data_block != 0
Attackers can cause a denial of service by mounting a crafted ext4 filesystem with unsupported bigalloc parameters, requiring kernel patching.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-31447?
CVE-2026-31447 is a high-severity denial of service vulnerability in Linux kernel, published on 22 Apr 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Official description
In the Linux kernel, the following vulnerability has been resolved:
ext4: reject mount if bigalloc with s_first_data_block != 0
bigalloc with s_first_data_block != 0 is not supported, reject mounting it.
Weakness: CWE-20
Which versions are affected by CVE-2026-31447?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-31447?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-31447 being exploited?
There is no known exploitation of CVE-2026-31447 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-83321, BELL-CVE-2026-31447, DEBIAN-CVE-2026-31447, GHSA-mgcw-5h4f-3529, ROOT-OS-DEBIAN-11-CVE-2026-31447, ROOT-OS-DEBIAN-12-CVE-2026-31447 and 4 more.