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THREAT OPS › Threat News › [NVD] CVE-2026-64391 (CRITICAL 9.8) — 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 LS

[NVD] CVE-2026-64391 (CRITICAL 9.8) — 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 LS

lownvdPublished 2026-07-25

CVE-2026-64391 CVSS: 9.8 CRITICAL Published: 2026-07-25T10:17:22.453

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.

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MITRE ATT&CK techniques

Indicators of compromise

Original source: https://nvd.nist.gov/vuln/detail/CVE-2026-64391