CVE-2021-3732

Local file disclosure via unrestricted private clones

Published Mar 7, 2022 · Updated Aug 3, 2024

Information disclosure in Linux Kernel OverlayFS allows local users to read hidden files through a crafted tmpfs mount. OverlayFS fails to restrict private clone mounts, allowing a tmpfs upper layer to expose files hidden in the original mount. Exploitation requires a low-privileged local account able to mount OverlayFS inside an unprivileged user namespace; the reported consequence is disclosure only.

CVSS severity5.5
Medium
EPSS probability0.33%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Information disclosure in Linux Kernel OverlayFS allows local users to read hidden files through a crafted tmpfs mount. OverlayFS fails to restrict private clone mounts, allowing a tmpfs upper layer to expose files hidden in the original mount. Exploitation requires a low-privileged local account able to mount OverlayFS inside an unprivileged user namespace; the reported consequence is disclosure only.

The record

CVE
CVE-2021-3732
Published
Mar 7, 2022
Updated
Aug 3, 2024
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-200, T1005
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 7, 2022CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record 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=Affects kernel before v5.13.11, Fixed in v5.14-rc6 and later.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=Affects kernel before v5.13.11, Fixed in v5.14-rc6 and later.

Published CVSS scores

5.5NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
3.3Amazon LinuxCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
5.5UbuntuCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
2.1NVDAV:L/AC:L/Au:N/C:P/I:N/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.

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

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-200Exposure of Sensitive Information to an Unauthorized Actor
T1005Data from Local System

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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