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NVD / CVE Program· CNA Linux

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

Noroxi assessment

Priority: Monitor (action score 39/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.49% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 222c4c52c3af2d0f68de31182710df3508a31095, 2ad5509dd576ae16d252d4698daf03002f9e0234, 2b4592cea214683de0f2ce6f8c22c097fb0ea1ab.

Low priority for now. Upgrade to Linux Linux 222c4c52c3af2d0f68de31182710df3508a31095, 2ad5509dd576ae16d252d4698daf03002f9e0234, 2b4592cea214683de0f2ce6f8c22c097fb0ea1ab or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

CriticalCVSS 9.8 · v3.1—No exploit Fix available
Published
Jul 25, 2026
Updated
Oct 30, 2026
EPSS
0.4% · 42th percentile
CWE
—

Report tools

JSON

Action score

39

Monitor

Low priority for now.

CVSS
39 / 40 · 9.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.4%

CNA vs NVD score

NVD
—
CNA · Linux
9.8
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-64391

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
linuxlinux kernel

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • linux linux kernel5.15 and later · before 6.12.96
  • linux linux kernel6.13 and later · before 6.18.39
  • linux linux kernel6.19 and later · before 7.1.4

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 5.15affected
    • f44158485826c076335d6860d35872271a83791d and later · before 222c4c52c3af2d0f68de31182710df3508a31095affected · git
    • f44158485826c076335d6860d35872271a83791d and later · before 2ad5509dd576ae16d252d4698daf03002f9e0234affected · git
    • f44158485826c076335d6860d35872271a83791d and later · before a8f5d39971bbad9340d49cd41b0e2da9452a649daffected · git
    • f44158485826c076335d6860d35872271a83791d and later · before 2b4592cea214683de0f2ce6f8c22c097fb0ea1abaffected · git
    • f44158485826c076335d6860d35872271a83791d and later · before 52a56cf53ec834c44ac1b4d16d585f26613ee5ceaffected · git
    • f44158485826c076335d6860d35872271a83791d and later · before baa5e094886fffa7e6272edcb5e08be5ce28262caffected · git
    • before 5.15not affected · semver
    • 6.1.191 and later · up to and including 6.1.*not affected · semver
    • 6.6.160 and later · up to and including 6.6.*not affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxfrom 0—
Debian:12linux-6.12before 6.12.100-1~deb12u16.12.100-1~deb12u1
Debian:13linuxbefore 6.12.96-16.12.96-1
Debian:14linuxbefore 7.1.4-17.1.4-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
    90Now
  • CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe KEV
    89Now
  • CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
    85Now

Published before and after this one in the same product

  • ← EarlierCVE-2026-64388Jul 25, 2026 · smb/client: fix chown/chgrp with SMB3 POSIX Extensions
    31Monitor
  • ← EarlierCVE-2026-64389Jul 25, 2026 · ksmbd: validate NTLMv2 response before updating session key
    32Monitor
  • Later →CVE-2026-64392Jul 25, 2026 · ksmbd: use opener credentials for delete-on-close
    36Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux222c4c52c3af2d0f68de31182710df3508a31095Vendor (CNA)
Linux Linux2ad5509dd576ae16d252d4698daf03002f9e0234Vendor (CNA)
Linux Linux2b4592cea214683de0f2ce6f8c22c097fb0ea1abVendor (CNA)
Linux Linux52a56cf53ec834c44ac1b4d16d585f26613ee5ceVendor (CNA)
Linux Linuxa8f5d39971bbad9340d49cd41b0e2da9452a649dVendor (CNA)
Linux Linuxbaa5e094886fffa7e6272edcb5e08be5ce28262cVendor (CNA)
debian:linux6.12.96-1 · Debian:13Package registry (OSV)
debian:linux-6.126.12.100-1~deb12u1 · Debian:12Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

—

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (5 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records