PatchTheCVECVE-2026-64391: In the Linux kernel, the following vulnerability has been resolved: ksmbd: use opener credentials for ADS I/O
CVE-2026-64391 is a critical-severity flaw (CVSS 9.8) affecting linux kernel. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
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.
Why this priority
- Critical severity
- Remotely exploitable, no login, no user action
- On your watchlist
A fixed release or distro patch exists.
Risk facts
| CVSS score | 9.8 (Critical) |
| Attack vector | Network (remote) |
| Attack complexity | Low |
| Privileges needed | None |
| User interaction | None |
| EPSS exploit chance | 0.5% (top 61%) |
| CISA exploited list | No |
| Published | 2026-07-25 |
| Last modified | 2026-10-21 |
Last updated 2026-10-21 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Am I affected?
Timeline
- Published CVE record published
- Updated Record last modified
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Quick answers
How do I fix CVE-2026-64391?
linux kernel: upgrade to 6.12.96, 6.18.39, 7.1.4. Exact commands for each OS are on this page.
Is CVE-2026-64391 being exploited?
CVE-2026-64391 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.
What does CVE-2026-64391 affect?
CVE-2026-64391 affects linux kernel. Severity is critical (CVSS 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 helper
How urgent is CVE-2026-64391?
Priority 54/100. Critical severity; Remotely exploitable, no login, no user action; On your watchlist
Software pages
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