CVE-2026-89638Hinoki check available

Privilege escalation via persistent setuid and setgid bits

Published Sep 11, 2026 · Updated Sep 11, 2026

Improper privilege management in the Linux kernel allows local users to gain privileges through a modified file on a CIFS mount. The cifs_setattr_unix() and cifs_setattr_nounix() paths discard ATTR_MODE while handling ATTR_KILL_SUID or ATTR_KILL_SGID, so the cleared mode is not sent to the server. The flaw requires cifsacl, modefromsid, SMB3.1.1 POSIX extensions, or SMB1 Unix extensions and leaves setuid or setgid bits effective for later execution.

CVSS severityUnavailable
Unscored
EPSS probability0.17%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Improper privilege management in the Linux kernel allows local users to gain privileges through a modified file on a CIFS mount. The cifs_setattr_unix() and cifs_setattr_nounix() paths discard ATTR_MODE while handling ATTR_KILL_SUID or ATTR_KILL_SGID, so the cleared mode is not sent to the server. The flaw requires cifsacl, modefromsid, SMB3.1.1 POSIX extensions, or SMB1 Unix extensions and leaves setuid or setgid bits effective for later execution.

The record

CVE
CVE-2026-89638
Published
Sep 11, 2026
Updated
Sep 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1548.001
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 11, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 11, 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=2.6.24
  2. Affected versionversion=d32c4f2626acc385d5187bd5c0c24f442328dc60 <69bfe810ecd1e0387d8975d711cd326341d13c6e
  3. Affected versionversion=d32c4f2626acc385d5187bd5c0c24f442328dc60 <b10015807e4c628095d1d1d1c9307efc8cdd9e1b
  4. Affected versionversion=d32c4f2626acc385d5187bd5c0c24f442328dc60 <b8e5dc4f95e5484159b343903f302eb6d783f2e6

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=2.6.24; version=d32c4f2626acc385d5187bd5c0c24f442328dc60 <69bfe810ecd1e0387d8975d711cd326341d13c6e; version=d32c4f2626acc385d5187bd5c0c24f442328dc60 <b10015807e4c628095d1d1d1c9307efc8cdd9e1b; version=d32c4f2626acc385d5187bd5c0c24f442328dc60 <b8e5dc4f95e5484159b343903f302eb6d783f2e6

Published CVSS scores

No CVSS assessment is available in this record.

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.

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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)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1548.001Setuid and Setgid

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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