Limited file write via unterminated directory prefix
Published Jan 26, 2022 · Updated Apr 22, 2025
Path traversal in ICSharpCode SharpZipLib 1.0.0 through 1.3.2 allows local users to write files outside a ZIP extraction directory. FastZip joins each ZIP entry name to _baseDirectory, then accepts the full path when it merely starts with that unterminated directory string. A crafted sibling path sharing the directory-name prefix bypasses the check, but filename and destination constraints limit which files can be created.
Summary
What happened
Path traversal in ICSharpCode SharpZipLib 1.0.0 through 1.3.2 allows local users to write files outside a ZIP extraction directory. FastZip joins each ZIP entry name to _baseDirectory, then accepts the full path when it merely starts with that unterminated directory string. A crafted sibling path sharing the directory-name prefix bypasses the check, but filename and destination constraints limit which files can be created.
The record
- CVE
- CVE-2021-32842
- Published
- Jan 26, 2022
- Updated
- Apr 22, 2025
- Vendor
- ICSharpCode
- Product
- SharpZipLib
- Classifications
- CWE-22
- Attack vector
- local
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jan 26, 2022CVE publishedPublication date reported by the CVE source.
- 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.
- Affected versionversion=1.0.0 <1.0.0*
- Affected versionversion=1.3.3 <1.3.3
What conditions does exploitation require?
What is affected?
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.
Weakness, pattern, technique
Public exploit references
- GitHub Security Lab crafted ZIP traversal demonstrationproof of concept · demonstrated
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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