Partial path traversal in sharpcompress
SharpCompress recreates a hierarchy of directories under destinationDirectory if ExtractFullPath is set to true in options. In order to prevent extraction outside the destination directory the destinationFileName path is verified to begin with fullDestinationDirectoryPath. However it is not enforced that fullDestinationDirectoryPath ends with slash:
public static void WriteEntryToDirectory(IEntry entry,
string destinationDirectory,
ExtractionOptions? options,
Action<string, ExtractionOptions?> write)
{
string destinationFileName;
string file = Path.GetFileName(entry.Key);
string fullDestinationDirectoryPath = Path.GetFullPath(destinationDirectory);
...
throw new ExtractionException("Entry is trying to write a file outside of the destination directory.");
}If the destinationDirectory is not slash terminated like /home/user/dir it is possible to create a file with a name thats begins as the destination directory one level up from the directory, i.e. /home/user/dir.sh.
Impact
Because of the file name and destination directory constraints the arbitrary file creation impact is limited and depends on the use case.
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| .NET (NuGet) | SharpCompress | < 0.29 | 0.29 |
References
- https://github.com/adamhathcock/sharpcompress/security/advisories/GHSA-jp7f-grcv-6mjf
- https://nvd.nist.gov/vuln/detail/CVE-2021-39208
- https://github.com/adamhathcock/sharpcompress/pull/614
- https://github.com/adamhathcock/sharpcompress/commit/ea5c8dc06314c7a5068e7901c51a625224d2b288
- https://github.com/adamhathcock/sharpcompress
- https://github.com/adamhathcock/sharpcompress/releases/tag/0.29.0
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N- Weakness (CWE)
CWE-22- Platform
- .NET (NuGet)
- Package
SharpCompress- Disclosed
- 20.09.2021
- Updated
- 11.10.2026 11:23
Sources and licenses
OSV / GitHub Advisory Database - GHSA-jp7f-grcv-6mjf - CC BY 4.0
Vulnerability history: SharpCompress
All published vulnerabilities of this package (.NET (NuGet)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 3
- First → latest
- 09.2019 05.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Medium 3
Disclosures per year
- 2019: 1
- 2020: 0
- 2021: 1
- 2022: 0
- 2023: 0
- 2024: 0
- 2025: 0
- 2026: 1
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Partial path traversal in sharpcompress this entry
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