What’s Vulnerable › Vulnerabilities

CVE-2026-64391: ksmbd: use opener credentials for ADS I/O

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-07-25 · updated 2026-10-30

Description

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.

Affected products

• Linux kernel: from 5.15 before 6.12.96; from 6.13 before 6.18.39; from 6.19 before 7.1.4 — fixed in 6.12.96, 6.18.39, 7.1.4
• Linux: 5.15 — fixed in 7.2

How to fix

Upgrade to a fixed version: Linux kernel 6.12.96, 6.18.39, 7.1.4; Linux 7.2. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/222c4c52c3af2d0f68de31182710df3508a31095
• https://git.kernel.org/stable/c/2ad5509dd576ae16d252d4698daf03002f9e0234
• https://git.kernel.org/stable/c/2b4592cea214683de0f2ce6f8c22c097fb0ea1ab
• https://git.kernel.org/stable/c/52a56cf53ec834c44ac1b4d16d585f26613ee5ce
• https://git.kernel.org/stable/c/a8f5d39971bbad9340d49cd41b0e2da9452a649d
• https://git.kernel.org/stable/c/baa5e094886fffa7e6272edcb5e08be5ce28262c

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