CVE-2021-30833Public exploit

Arbitrary file write via symlinked archive paths

Published Oct 28, 2021 · Updated Aug 3, 2024

Path traversal in Apple macOS before 12.0 allows context-dependent attackers to write arbitrary files through a crafted XAR archive. The xar utility accepts a slash-separated file name beneath an archived directory symlink and resolves extraction through that symlink outside the destination. A user must extract the archive, and writes are limited to locations permitted by that user's filesystem access.

CVSS severity5.5
Medium
EPSS probability42.67%
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 Apple macOS before 12.0 allows context-dependent attackers to write arbitrary files through a crafted XAR archive. The xar utility accepts a slash-separated file name beneath an archived directory symlink and resolves extraction through that symlink outside the destination. A user must extract the archive, and writes are limited to locations permitted by that user's filesystem access.

The record

CVE
CVE-2021-30833
Published
Oct 28, 2021
Updated
Aug 3, 2024
Vendor
Apple
Product
macOS
Classifications
T1204.002
Attack vector
local
Privileges
Unavailable

Timeline

How it unfolded

  1. Oct 28, 2021CVE 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=unspecified <12.0

What conditions does exploitation require?

Attack vectorlocal
Required privilegesUnavailable in this record.

What is affected?

Apple · macOSversion=unspecified <12.0

Published CVSS scores

4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:P/A:N
5.0NCC GroupCVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:N/I:H/A:N
5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:H/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

T1204.002Malicious 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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