CVE-2026-90176Network attack vectorHinoki check available

Authenticated file access via skipped single-byte lock checks

Published Sep 17, 2026 · Updated Sep 18, 2026

Improper lock enforcement in affected Linux ksmbd versions allows remote authenticated users to bypass conflicting byte-range locks. The check_lock_range() function treats start == end as empty even though its inclusive range represents one byte, so reads, writes, copychunk requests, and truncation skip conflict checks. An authenticated SMB session must target a locked byte; successful requests can read or modify that byte despite another client's mandatory lock.

CVSS severity8.1
High
EPSS probability0.50%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Improper lock enforcement in affected Linux ksmbd versions allows remote authenticated users to bypass conflicting byte-range locks. The check_lock_range() function treats start == end as empty even though its inclusive range represents one byte, so reads, writes, copychunk requests, and truncation skip conflict checks. An authenticated SMB session must target a locked byte; successful requests can read or modify that byte despite another client's mandatory lock.

The record

CVE
CVE-2026-90176
Published
Sep 17, 2026
Updated
Sep 18, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-362, T1565.001, T1039
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 17, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 18, 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=52fcbb92e0d3acfd1448b2a43b6595d540da5295 <a89cc145832e81c32199d4ca2e1ea8bd51ed601d
  2. Affected versionversion=571204e4758a528fbd67330bd4b0dfbdafb33dd8 <84c2d8e807ac489f5c91769293fb15dfdae8bae8
  3. Affected versionversion=5d510ac31626ed157d2182149559430350cf2104 <07a9e289ff7edcc004f58952405f8a65c4e37512
  4. Affected versionversion=5d510ac31626ed157d2182149559430350cf2104 <d40c24634fe077a0dc91fd11fccf44ce12b454d5
  5. Affected versionversion=6.1.160 <6.1.188
  6. Affected versionversion=6.12.64 <6.12.110
  7. Affected versionversion=6.18.3 <6.18.52
  8. Affected versionversion=6.19
  9. Affected versionversion=6.6.120 <6.6.157
  10. Affected versionversion=a6f4cfa3783804336491e0edcb250c25f9b59d33 <f751d6e39d4c937c45f8fedc66699aa7d2d52288
  11. Affected versionversion=da29cd197246c85c0473259f1cad897d9d28faea <993e0158331d37c04da18efe551b5e1e35fb3078

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=52fcbb92e0d3acfd1448b2a43b6595d540da5295 <a89cc145832e81c32199d4ca2e1ea8bd51ed601d; version=571204e4758a528fbd67330bd4b0dfbdafb33dd8 <84c2d8e807ac489f5c91769293fb15dfdae8bae8; version=5d510ac31626ed157d2182149559430350cf2104 <07a9e289ff7edcc004f58952405f8a65c4e37512; version=5d510ac31626ed157d2182149559430350cf2104 <d40c24634fe077a0dc91fd11fccf44ce12b454d5; version=6.1.160 <6.1.188; version=6.12.64 <6.12.110; version=6.18.3 <6.18.52; version=6.19; version=6.6.120 <6.6.157; version=a6f4cfa3783804336491e0edcb250c25f9b59d33 <f751d6e39d4c937c45f8fedc66699aa7d2d52288; version=da29cd197246c85c0473259f1cad897d9d28faea <993e0158331d37c04da18efe551b5e1e35fb3078

Published CVSS scores

8.1Linux kernel CVE teamCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

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

CWE-362Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
T1565.001Stored Data Manipulation
T1039Data from Network Shared Drive

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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