VulnerabilityPublished 17 Sep 2026Updated 30 Oct 2026

CVE-2026-90155: Linux kernel · ksmbd: detach blocked lock requests before freeing

Source GCVE Database

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Authoritative record:CVE-2026-90155· Medium

Not known to be exploited · fixed in f77d2accafca529e0ea3f979eb6e6cf1dac05c90 : update Linux kernel when convenient.

Data as of 30 Oct 2026, 19:05 UTC

Severity

Medium

Rated Medium by Threat Radar's AI analysis · CVSS not yet scored by NVD

Thin evidence

One scorer or none

Patch: Available – fixed in f77d2accafca529e0ea3f979eb6e6cf1dac05c90, d31db79cfaa9fce6649772ad279779473ba8aef9, d20d3f6ad8b0b6f4e1bb32cdf7eca251962e8f04 +3

Exploitation evidence

Disclosed: evidence found.
CVE published 17 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

ghsa-52g3-8w7f-v5w2

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ d63528eb0d43c4796c42aad56889dec12cf4e122, < f77d2accafca529e0ea3f979eb6e6cf1dac05c90	Fixed in f77d2accafca529e0ea3f979eb6e6cf1dac05c90
LinuxLinux	Affected ≥ d63528eb0d43c4796c42aad56889dec12cf4e122, < d31db79cfaa9fce6649772ad279779473ba8aef9	Fixed in d31db79cfaa9fce6649772ad279779473ba8aef9
LinuxLinux	Affected ≥ d63528eb0d43c4796c42aad56889dec12cf4e122, < d20d3f6ad8b0b6f4e1bb32cdf7eca251962e8f04	Fixed in d20d3f6ad8b0b6f4e1bb32cdf7eca251962e8f04
LinuxLinux	Affected ≥ d63528eb0d43c4796c42aad56889dec12cf4e122, < 514a0b2bc949963497e66cacd433f65dc768a71d	Fixed in 514a0b2bc949963497e66cacd433f65dc768a71d
LinuxLinux	Affected ≥ d63528eb0d43c4796c42aad56889dec12cf4e122, < 215e8816b1ac25176d911abb8704390413ccee4b	Fixed in 215e8816b1ac25176d911abb8704390413ccee4b
LinuxLinux	Affected ≥ d63528eb0d43c4796c42aad56889dec12cf4e122, < 4e8b69c06bd6583ec11abef4fae50c2c8d5f3679	Fixed in 4e8b69c06bd6583ec11abef4fae50c2c8d5f3679

AI-suggested

A fix has been implemented to detach blocked file_lock requests before freeing them in the close, cross-request unlock, and rollback paths within ksmbd. Users should apply the official Linux kernel updates that include this fix once available.

Description

A vulnerability in the Linux kernel's ksmbd component involves improper handling of blocked file lock requests. Specifically, file_lock objects retained for byte-range lock bookkeeping may still be linked in the VFS blocked-request graph when freed, causing potential kernel bugs. The issue arises because the ksmbd_file reference count does not cover the entire blocked-request graph, leading to a lifetime mismatch and kernel BUG_ON triggers during lock release operations. The fix involves detaching these file_lock objects from the blocked-request graph before freeing them.

Impact

This vulnerability can cause kernel crashes (BUG_ON triggers) due to improper handling of blocked lock requests in the ksmbd subsystem. Such crashes can lead to denial of service conditions on affected systems running the vulnerable Linux kernel versions. There is no indication of code execution or privilege escalation from the provided data.

Summary

The vulnerability in the Linux kernel's ksmbd subsystem concerns the improper detachment of blocked file_lock requests before freeing them. The ksmbd retains file_lock objects for byte-range lock bookkeeping, but these objects may still be part of the VFS blocked-request graph, which can chain new waiters below blocked requests. Since the ksmbd_file reference count does not cover this graph, freeing these file_lock objects while dependent waiters remain attached leads to kernel BUG_ON conditions. The flaw affects the close, cross-request unlock, and rollback paths. The resolution involves detaching the file_lock from the blocked-request graph prior to freeing it, preventing kernel crashes and ensuring proper lock lifecycle management.

References

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