Partial path traversal in sharpcompress

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

5.3 · CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2021-39208: 1.19% estimated exploitation activity in the next 30 days; percentile 68.03 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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: 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.

Published by the source

20 Sep 2021, 19:53 UTC

Last modified by the source

6 Aug 2024, 05:07 UTC

Source last checked

26 Oct 2026, 17:00 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-jp7f-grcv-6mjf

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# Patch Next advisory brief: CVE-2021-39208

Advisory: Partial path traversal in sharpcompress
IDs: CVE-2021-39208, GHSA-jp7f-grcv-6mjf
Record: https://patchnext.com/advisories/cve-2021-39208 (revision 1, source checked 26 Oct 2026, 17:00 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: sharpcompress 0.29. A vendor fix does not mean a deployment is fixed.

## Affected components
- NuGet sharpcompress: affected < 0.29; fixed in 0.29

## Suggested inspection (read-only)
- NuGet sharpcompress: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on sharpcompress.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-jp7f-grcv-6mjf (GitHub-reviewed advisory GHSA-jp7f-grcv-6mjf lists affected ranges: NuGet sharpcompress >=0 <0.29)

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