CVE-2021-41072Public exploitNetwork attack vector

File overwrite via duplicate symlink entries

Published Sep 14, 2021 · Updated Aug 4, 2024

Path traversal in Squashfs-Tools 4.5 allows attackers to overwrite files outside the extraction directory via a crafted Squashfs image. squashfs_opendir accepts duplicate directory entries, so extraction creates an outward-pointing symbolic link and then follows it when writing the same-named regular file. Exploitation requires processing the image with unsquashfs, and the overwrite is limited to paths writable by that process.

CVSS severity8.1
High
EPSS probability2.30%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Path traversal in Squashfs-Tools 4.5 allows attackers to overwrite files outside the extraction directory via a crafted Squashfs image. squashfs_opendir accepts duplicate directory entries, so extraction creates an outward-pointing symbolic link and then follows it when writing the same-named regular file. Exploitation requires processing the image with unsquashfs, and the overwrite is limited to paths writable by that process.

The record

CVE
CVE-2021-41072
Published
Sep 14, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-59, T1204.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 14, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

8.1NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H
5.8NVDAV:N/AC:M/Au:N/C:N/I:P/A:P

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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-59Improper Link Resolution Before File Access ('Link Following')
T1204.002User Execution: Malicious File

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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