High 7.8Published Jun 24, 2026

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

Updated under an hour ago (Oct 27, 2026, 11:30 PM ET)

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Exploited in the last 30 days

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.

CVSS: 7.8 HIGH (v3.1, CNA)CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Weakness (CWE): Not given
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Linux
NVD analysis: Analyzed
Record last updated: Aug 5, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Linux Linux linux:linux (from the name)	from a3ab7155ea21aadc8a4d5687e91b3d876973185e before fbc72f5c645155dc2ed3573243ed20f9913e3a54; from a3ab7155ea21aadc8a4d5687e91b3d876973185e before 5822a05a841a10794ad818620dd2af490b0705d3; from a3ab7155ea21aadc8a4d5687e91b3d876973185e before 754ff1bea3819a90c6f33cccfc1a299ef7609f07; from a3ab7155ea21aadc8a4d5687e91b3d876973185e before 131ea3e57fc22936ed0e2c8330f2e36106172f51; from a3ab7155ea21aadc8a4d5687e91b3d876973185e before 79f84af38c9fef9deb0e02c79eb969b5541c2644; from a3ab7155ea21aadc8a4d5687e91b3d876973185e before 6561afc38398e3518a29c5eebb975c30468f98a6; from a3ab7155ea21aadc8a4d5687e91b3d876973185e before 817f16ed62bc58a168417bfb5e859c2a370bab03; from a3ab7155ea21aadc8a4d5687e91b3d876973185e before 0621c385fda1376e967f37ccd534c26c3e511d14	CNA record
linux linux_kernel linux:linux_kernel	from 2.6.27 before 5.10.258; from 5.11 before 5.15.209; from 5.16 before 6.1.175; from 6.2 before 6.6.141; from 6.7 before 6.12.91; from 6.13 before 6.18.33; from 6.19 before 7.0.10	NVD

References

References

https://git.kernel.org/stable/c/fbc72f5c645155dc2ed3573243ed20f9913e3a54	patch
https://git.kernel.org/stable/c/5822a05a841a10794ad818620dd2af490b0705d3	patch
https://git.kernel.org/stable/c/754ff1bea3819a90c6f33cccfc1a299ef7609f07	patch
https://git.kernel.org/stable/c/131ea3e57fc22936ed0e2c8330f2e36106172f51	patch
https://git.kernel.org/stable/c/79f84af38c9fef9deb0e02c79eb969b5541c2644	patch
https://git.kernel.org/stable/c/6561afc38398e3518a29c5eebb975c30468f98a6	patch
https://git.kernel.org/stable/c/817f16ed62bc58a168417bfb5e859c2a370bab03	patch
https://git.kernel.org/stable/c/0621c385fda1376e967f37ccd534c26c3e511d14	patch

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.