TI-2021-12507 Aliases CVE-2021-32842 GHSA-mm6g-mmq6-53ff

Path Traversal in SharpZipLib

MEDIUM 57CWE-22Published 2022-01-26 · Updated 2025-04-22

Key facts

Attack vector: Network
Privileges required: None
User interaction: None
Attack complexity: Low
Impact type: —
Confidentiality · integrity · availability: None · Low · None
Fix status: Fixed

Attack profile from CVSS 3.1 · NVD. Fix status from CNA and GitHub.

Summary

SharpZipLib (or #ziplib) is a Zip, GZip, Tar and BZip2 library. Starting version 1.0.0 and prior to version 1.3.3, a check was added if the destination file is under a destination directory. However, it is not enforced that `_baseDirectory` ends with slash. If the _baseDirectory 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`. Because of the file name and destination directory constraints, the arbitrary file creation impact is limited and depends on the use case. Version 1.3.3 fixed this vulnerability.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV

EPSS 0.00895 59th percentileScored 2026-11-07

Public exploit Yes 1 exploit referenceTagged by NVD

Fix Fixed sharpziplib (icsharpcode): 1.3.3SharpZipLib (NuGet): 1.3.3

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: Poc
Automatable: No
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
icsharpcode	sharpziplib	1.3.3 to before 1.3.3; 1.0.0 and later	1.3.3	Patch available	CNA
—	SharpZipLib (NuGet)	1.0.0 to before 1.3.3	1.3.3	Patch available	GHSA-mm6g-mmq6-53ff

sharpziplib Vendoricsharpcode Affected 1.3.3 to before 1.3.3; 1.0.0 and later Fixed in 1.3.3 Patch available CNA
SharpZipLib (NuGet) Vendor— Affected 1.0.0 to before 1.3.3 Fixed in 1.3.3 Patch available GHSA-mm6g-mmq6-53ff

CPE configurations NVD · 1

CPE	Versions	Role	Vendor
cpe:2.3:a:sharpziplib_project:sharpziplib::::::::	1.0.0 to before 1.3.3	Vulnerable	icsharpcode

cpe:2.3:a:sharpziplib_project:sharpziplib:*:*:*:*:*:*:*:* Versions 1.0.0 to before 1.3.3 Vulnerable ·icsharpcode

Remediation

Fix · CNA sharpziplib (icsharpcode) Fixed in 1.3.3
Fix · GHSA-mm6g-mmq6-53ff SharpZipLib (NuGet) Fixed in 1.3.3 Advisory →

Timeline

2026-10-02 Threatist record created from CVE-2021-32842
2026-10-03 Alias added: GHSA-mm6g-mmq6-53ff

References

Exploit 1

https://securitylab.github.com/advisories/GHSL-2021-125-sharpziplib/

Advisory 3

Other 1

https://github.com/icsharpcode/SharpZipLib

TI-2021-12505 Path Traversal in SharpZipLib CVSS 3.1CRITICAL 9.8
TI-2021-12506 Path Traversal in SharpZipLib CVSS 3.1MEDIUM 5.3
TI-2018-16140 Path traversal in SharpZipLib CVSS 3.1MEDIUM 5.5

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences