CVE-2026-90155Network attack vector

Kernel crash via premature byte-range lock freeing

Published Sep 17, 2026 · Updated Sep 17, 2026

Lock-lifetime errors in ksmbd in Linux 5.15 allow remote authenticated users to crash kernel execution via SMB byte-range locks. The __ksmbd_close_fd() and cross-request unlock paths free file_lock objects while dependent VFS waiters remain attached, triggering BUG_ON in locks_release_private() and leaving stale lock references. Exploitation requires an enabled ksmbd server, share access, and overlapping blocked lock requests; the grounded consequence is interrupted availability, not demonstrated code execution.

CVSS severity5.3
Medium
EPSS probability0.21%
Next 30 days · Oct 18, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Lock-lifetime errors in ksmbd in Linux 5.15 allow remote authenticated users to crash kernel execution via SMB byte-range locks. The __ksmbd_close_fd() and cross-request unlock paths free file_lock objects while dependent VFS waiters remain attached, triggering BUG_ON in locks_release_private() and leaving stale lock references. Exploitation requires an enabled ksmbd server, share access, and overlapping blocked lock requests; the grounded consequence is interrupted availability, not demonstrated code execution.

The record

CVE
CVE-2026-90155
Published
Sep 17, 2026
Updated
Sep 17, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499.004
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 17, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 17, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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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=d63528eb0d43c4796c42aad56889dec12cf4e122 <215e8816b1ac25176d911abb8704390413ccee4b
  3. Affected versionversion=d63528eb0d43c4796c42aad56889dec12cf4e122 <514a0b2bc949963497e66cacd433f65dc768a71d

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.15; version=d63528eb0d43c4796c42aad56889dec12cf4e122 <215e8816b1ac25176d911abb8704390413ccee4b; version=d63528eb0d43c4796c42aad56889dec12cf4e122 <514a0b2bc949963497e66cacd433f65dc768a71d

Published CVSS scores

5.3Amazon LinuxCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Activity data is delayed. The latest report is Sep 28, 2026.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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