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.
CSIRTS triage
- What
- The ksmbd service does not use opener credentials for ADS I/O.
- Who is affected
- Deployments using ksmbd.
- Urgency
- Remediation is necessary to ensure proper access control.
- Action
- Apply the relevant patches once available.
AI-assisted analysis generated from the source advisory — verify against the original.
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Exploitation outlook
- Low exploitation risk0.46% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 37% of all EPSS-scored CVEs.
Advisory coverage (2)
- criticalCVE-2026-64391: In the Linux kernel, the following vulnerability has been resolved: ksmbd: use opener credenti…nvd · 2026-07-25
- highCVE-2026-64391: ksmbd: use opener credentials for ADS I/Omsrc · 2026-07-14
External references
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