CVE-2026-53130 fs/omfs: reject s_sys_blocksize smaller than OMFS_DIR_START

High 7.8 Published 24 Jun 2026 Updated 5 Aug 2026

A local attacker can trigger a kernel memory corruption via a crafted OMFS filesystem image, potentially leading to code execution or system crash.

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-2026-53130?

CVE-2026-53130 is a high-severity vulnerability in Linux kernel, published on 24 Jun 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:

fs/omfs: reject s_sys_blocksize smaller than OMFS_DIR_START

omfs_fill_super() rejects oversized s_sys_blocksize values (> PAGE_SIZE), but it does not reject values smaller than OMFS_DIR_START (0x1b8 = 440).

Later, omfs_make_empty() uses

sbi->s_sys_blocksize - OMFS_DIR_START

as the length argument to memset(). Since s_sys_blocksize is u32, a crafted filesystem image with s_sys_blocksize < OMFS_DIR_START causes an unsigned underflow there, wrapping to a value near 2^32. That drives a ~4 GiB memset() from bh->b_data + OMFS_DIR_START and overwrites kernel memory far beyond the backing block buffer.

Add the corresponding lower-bound check alongside the existing upper-bound check in omfs_fill_super(), so that malformed images are rejected during superblock validation before any filesystem data is processed.

Weakness: CWE-191

Which versions are affected by CVE-2026-53130?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2026-53130?

Apply the vendor's patch.

Is CVE-2026-53130 being exploited?

There is no known exploitation of CVE-2026-53130 in the wild and no public exploit code.

All Linux kernel vulnerabilities

Sources

Also known as BELL-CVE-2026-53130, DEBIAN-CVE-2026-53130, GHSA-2j9j-p8f4-hwp3, ROOT-OS-DEBIAN-11-CVE-2026-53130, ROOT-OS-DEBIAN-12-CVE-2026-53130, ROOT-OS-UBUNTU-2204-CVE-2026-53130 and 2 more.