CVE-2021-4037

Local privilege escalation via incorrect XFS SGID inheritance

Published Aug 24, 2022 · Updated Aug 10, 2026

Improper access control in Linux Kernel XFS before 5.4.241 or 5.5 through 5.10.145 allows local users to gain excessive file permissions. The inode_init_owner() path assigns a new XFS file the parent directory's group and preserves group-execute and SGID bits even when its creator does not belong to that group. Exploitation requires a writable SGID directory on XFS owned by a group outside the local user's memberships, and the resulting file gains unintended group permissions.

CVSS severity4.4
Medium
EPSS probability0.31%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper access control in Linux Kernel XFS before 5.4.241 or 5.5 through 5.10.145 allows local users to gain excessive file permissions. The inode_init_owner() path assigns a new XFS file the parent directory's group and preserves group-execute and SGID bits even when its creator does not belong to that group. Exploitation requires a writable SGID directory on XFS owned by a group outside the local user's memberships, and the resulting file gains unintended group permissions.

The record

CVE
CVE-2021-4037
Published
Aug 24, 2022
Updated
Aug 10, 2026
Vendor
Red Hat
Product
Red Hat Enterprise Linux 8
Classifications
CWE-284, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 24, 2022CVE publishedPublication date reported by the CVE source.
  2. Aug 10, 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?

Affected versions are unavailable in this record. Check the vendor advisory for version and patch details.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Red Hat · Red Hat Enterprise Linux 8Affected versions are unavailable in this record.
Red Hat · Red Hat Enterprise Linux 8.4 Extended Update SupportAffected versions are unavailable in this record.
The Linux Kernel Organization · Linux Kernelversion=* <5.4.241; version=5.5 <5.10.146

Published CVSS scores

4.4Red HatCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/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.

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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

CWE-284Improper Access Control
T1068Exploitation for Privilege Escalation

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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