CVE-2026-64390Network attack vector

Kernel memory corruption via mislocked lock removal

Published Jul 25, 2026 · Updated Jul 25, 2026

Use-after-free in Linux Kernel ksmbd allows remote authenticated users to corrupt kernel memory through SMB3 multichannel byte-range locks. Final-close and durable-handle paths remove a lock entry while holding the opener connection's spinlock instead of the lock-owning connection's spinlock. A valid non-guest SMB3 session, signed multichannel binding, authorized tree connection, and accessible file handle are required; concurrent traversal can disclose kernel memory, enable arbitrary writes or code execution, or cause panics and hangs.

CVSS severity8.8
High
EPSS probability0.47%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in Linux Kernel ksmbd allows remote authenticated users to corrupt kernel memory through SMB3 multichannel byte-range locks. Final-close and durable-handle paths remove a lock entry while holding the opener connection's spinlock instead of the lock-owning connection's spinlock. A valid non-guest SMB3 session, signed multichannel binding, authorized tree connection, and accessible file handle are required; concurrent traversal can disclose kernel memory, enable arbitrary writes or code execution, or cause panics and hangs.

The record

CVE
CVE-2026-64390
Published
Jul 25, 2026
Updated
Jul 25, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
T1210
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jul 25, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 25, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=5.15
  2. Affected versionversion=f5a544e3bab78142207e0242d22442db85ba1eff <22d38cf75b556c20b039743bdf3654d535b858be
  3. Affected versionversion=f5a544e3bab78142207e0242d22442db85ba1eff <427faaa52b0b399940c1a88065a5c310d10dad15
  4. Affected versionversion=f5a544e3bab78142207e0242d22442db85ba1eff <5fecc15a30cb9ebd310f7b52c1ab607edcea78f6
  5. Affected versionversion=f5a544e3bab78142207e0242d22442db85ba1eff <66eb3643164e5e1029907793926c132f8b5c6148
  6. Affected versionversion=f5a544e3bab78142207e0242d22442db85ba1eff <c1016dd1d8b2bcd1158bbaabe94a31bb7e7431fb
  7. Affected versionversion=f5a544e3bab78142207e0242d22442db85ba1eff <ea5c9bf99f626a15cc59f645dc895f2b3f01992e
  8. Affected versionversion=f5a544e3bab78142207e0242d22442db85ba1eff <fe20d492a69a6f79e637f438072b212e21ed3b78

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=5.15; version=f5a544e3bab78142207e0242d22442db85ba1eff <22d38cf75b556c20b039743bdf3654d535b858be; version=f5a544e3bab78142207e0242d22442db85ba1eff <427faaa52b0b399940c1a88065a5c310d10dad15; version=f5a544e3bab78142207e0242d22442db85ba1eff <5fecc15a30cb9ebd310f7b52c1ab607edcea78f6; version=f5a544e3bab78142207e0242d22442db85ba1eff <66eb3643164e5e1029907793926c132f8b5c6148; version=f5a544e3bab78142207e0242d22442db85ba1eff <c1016dd1d8b2bcd1158bbaabe94a31bb7e7431fb; version=f5a544e3bab78142207e0242d22442db85ba1eff <ea5c9bf99f626a15cc59f645dc895f2b3f01992e; version=f5a544e3bab78142207e0242d22442db85ba1eff <fe20d492a69a6f79e637f438072b212e21ed3b78

Published CVSS scores

8.8kernel.orgCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1210Exploitation of Remote Services

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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