CVE-2021-32840Public exploit

Arbitrary file write via unchecked TAR entry paths

Published Jan 26, 2022 · Updated Apr 22, 2025

Path traversal in SharpZipLib before 1.3.3 allows attackers to write files outside the extraction directory through crafted TAR entries. TarArchive.ExtractContents combines an entry name such as ../evil.txt with destFolder without verifying that the resolved path remains beneath it. A consuming application must extract attacker-controlled TAR content; overwritten or planted files can enable code execution in that application's context.

CVSS severity7.3
High
EPSS probability1.97%
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 SharpZipLib before 1.3.3 allows attackers to write files outside the extraction directory through crafted TAR entries. TarArchive.ExtractContents combines an entry name such as ../evil.txt with destFolder without verifying that the resolved path remains beneath it. A consuming application must extract attacker-controlled TAR content; overwritten or planted files can enable code execution in that application's context.

The record

CVE
CVE-2021-32840
Published
Jan 26, 2022
Updated
Apr 22, 2025
Vendor
ICSharpCode
Product
SharpZipLib
Classifications
CWE-22, T1203
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 26, 2022CVE publishedPublication date reported by the CVE source.
  2. Apr 22, 2025Record 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=0.86.0 <0.86.0*
  2. Affected versionversion=1.3.3 <1.3.3

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

ICSharpCode · SharpZipLibversion=0.86.0 <0.86.0*; version=1.3.3 <1.3.3

Published CVSS scores

9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.5NIST NVDAV:N/AC:L/Au:N/C:P/I:P/A:P
7.3GitHub, Inc.CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:L/I:H/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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
T1203Exploitation for Client Execution

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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