Vulnerability in Linux

CVE-2026-64391

In the Linux kernel, the following vulnerability has been resolved: ksmbd: use opener credentials for ADS I/O Alternate data streams are stored as xattrs. Unlike regular file I/O, their read and write paths therefore call VFS xattr helpers which recheck inode permissions and LSM policy using the current task credentials. Run ADS I/O with the credentials captured when the SMB handle was opened.

EPSS: 0.005 (38.2th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

Affected products

References

Frequently asked questions

What is CVE-2026-64391?
CVE-2026-64391 is a critical-severity vulnerability in Linux. CVSS score: 9.8/10. Published 2026-07-25.
How severe is CVE-2026-64391?
Critical severity. CVSS v3 base score is 9.8 out of 10.