SB20260727134 - Out-of-bounds write in Linux kernel ntfs

Description

This security bulletin contains information about 1 vulnerability.

1) Out-of-bounds write (CVE-ID: CVE-2026-64431)

CWE-ID: CWE-787 - Out-of-bounds write

CVSSv4: 6.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]

The vulnerability allows a local user to cause a denial of service.

The vulnerability exists due to an out-of-bounds memory access in post_write_mst_fixup() in the NTFS index handling code when processing a crafted NTFS image containing an invalid index_block. A local user can supply a malicious NTFS image with crafted index_block metadata to cause a denial of service.

The issue can be triggered by malformed usa_ofs or usa_count values, including values that cause integer underflow or reference data outside the ntfs_record.

Remediation

Install update from vendor's website.

References

• https://git.kernel.org/stable/c/5b6eedd7cc2936f9238e852b553a1b326105bde8
• https://git.kernel.org/stable/c/e2018628301a6d9f54e34b0cb417f1688c66df1d