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CVE-2021-32842

Path Traversal in SharpZipLib

Public exploit available. Not confirmed exploited in the wild yet. Fixed versions are out.

CVSS 3.14.0MediumEPSS percentile59th0.9% chance in 30 daysCISA KEVNot listedNo confirmed exploitation
Public exploit: 1 sourceFix3 products2 fixed builds listed below

Published Updated Sources: CVE.org, NVD, GitHub

NVD CVE.org

What to do

Find your product and version, then upgrade to the build on the right.

  • Icsharpcode SharpziplibAffected: ≥ 1.3.3, < 1.3.3Upgrade to: 1.3.3Affected: ≥ 1.0.0, < 1.0.0*Upgrade to: 1.0.0*Stated by: CVE record
  • NuGet SharpZipLibAffected: ≥ 1.0.0, < 1.3.3Upgrade to: 1.3.3Stated by: GitHub advisory
  • Sharpziplib Project SharpziplibAffected: ≥ 1.0.0, < 1.3.3Upgrade to: 1.3.3Stated by: NVD

Versions as the sources state them. Full version matrix after sign-in

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What it is

From the CVE record

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.

In plain language

No plain-language summary for this CVE yet.

Exploitation

Where each signal puts this CVE on the scale from published to confirmed exploited.

EPSS59th
Public exploit
CISA KEV

Not in the catalog. CISA has not confirmed exploitation.

Public exploits

1 source with a proof of concept or module.

Exploit links, PoCs and Metasploit modules after sign-in
EPSS

0.9% chance of exploitation activity in the next 30 days, which ranks it in the 59th percentile of scored CVEs.

Exploit Prediction Scoring System, FIRST.org. A probability, not a confirmation.

Lifecycle

The patch came 471 days before any public exploit.

  1. Public exploit / PoCsource: github-poc
  2. Patch availablerecord updated
  3. Publishedweakness classified, att&ck mapped

Affected products

Technical detail

CVSS 3.1 vector

Open in the CVSS calculator

CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Scored 4.0 by NVD.

How it is reached

  • Attack Vector LocalRequires local access to the vulnerable system (e.g. local login, malicious file)
  • Attack Complexity LowNo special conditions — the attack can be reliably reproduced
  • Privileges Required NoneNo authentication required — anyone can exploit this
  • User Interaction NoneNo user interaction needed — fully automated exploitation

Scope

  • Scope UnchangedImpact is limited to the vulnerable component itself

Impact if exploited

  • Confidentiality NoneNo confidentiality impact
  • Integrity LowData modification is possible but limited in scope or consequence
  • Availability NoneNo availability impact

Weaknesses

ATT&CK techniques

Mapped from the weaknesses above (CWE to ATT&CK), not observed in attacks.

Sources

References in the record

And 2 more references. See all after sign-in

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We'll flag the next CVE, public exploit or patch for Sharpziplib, not every advisory. This one: public exploit.