CVE-2021-41091Public exploit

Local privilege escalation via traversable container layers

Published Oct 4, 2021 · Updated Aug 4, 2024

Incorrect directory permissions in Moby before 20.10.9 allow local users to execute setuid programs from container layers. The daemon created its root, container, mount, and graph-driver directories with mode 0701, granting every host user traversal; the patch changes them to 0710 and assigns the remapped root group. Exploitation requires a container layer with a setuid executable, while a colliding host UID or GID also permits that local user to read or modify matching files.

CVSS severity6.3
Medium
EPSS probability2.85%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Incorrect directory permissions in Moby before 20.10.9 allow local users to execute setuid programs from container layers. The daemon created its root, container, mount, and graph-driver directories with mode 0701, granting every host user traversal; the patch changes them to 0710 and assigns the remapped root group. Exploitation requires a container layer with a setuid executable, while a colliding host UID or GID also permits that local user to read or modify matching files.

The record

CVE
CVE-2021-41091
Published
Oct 4, 2021
Updated
Aug 4, 2024
Vendor
Moby Project
Product
Moby
Classifications
CWE-732, CWE-281, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Oct 4, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 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=< 20.10.9

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Moby Project · Mobyversion=< 20.10.9

Published CVSS scores

4.6NIST NVDAV:L/AC:L/Au:N/C:P/I:P/A:P
5.9Moby GitHub Security AdvisoryCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
6.3GitHub CNACVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:L

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 exploitPublished

Weakness, pattern, technique

CWE-732Incorrect Permission Assignment for Critical Resource
CWE-281Improper Preservation of Permissions
T1068Exploitation for Privilege Escalation

Public exploit references

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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