CVE-2021-23521

Arbitrary file write via followed archive symlink

Published Jan 31, 2022 · Updated Sep 17, 2024

Link following in JUCE before 6.1.5 allows local users to write arbitrary files outside an extraction directory via a crafted ZIP archive. ZipFile::uncompressEntry in juce_ZipFile.cpp follows a symbolic-link component beneath the destination instead of rejecting the resolved path before uncompressTo() writes the entry. Exploitation requires a malicious archive to be extracted by a process with access to the targeted path; overwriting a security-sensitive file can lead to code execution.

CVSS severity7.8
High
EPSS probability0.54%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Link following in JUCE before 6.1.5 allows local users to write arbitrary files outside an extraction directory via a crafted ZIP archive. ZipFile::uncompressEntry in juce_ZipFile.cpp follows a symbolic-link component beneath the destination instead of rejecting the resolved path before uncompressTo() writes the entry. Exploitation requires a malicious archive to be extracted by a process with access to the targeted path; overwriting a security-sensitive file can lead to code execution.

The record

CVE
CVE-2021-23521
Published
Jan 31, 2022
Updated
Sep 17, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-59
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 31, 2022CVE publishedPublication date reported by the CVE source.
  2. Sep 17, 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 vectorlocal
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.8NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
4.6NIST NVDAV:L/AC:L/Au:N/C:P/I:P/A:P
5.5SnykCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/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.

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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-59Improper Link Resolution Before File Access ('Link Following')

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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