Is CVE-2018-20835 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2018-20835 being exploited in the wild.

How severe is CVE-2018-20835?

Low severity, with a CVSS score of 3, published 1 May 2019.

Which products and versions are affected?

tar-fs (npm) SEMVER:introduced=0,fixed=1.16.2.

Is there a fix for CVE-2018-20835?

Yes. tar-fs (npm): upgrade to 1.16.2 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2018-20835 attacked?

It is attacked over the network.

Am I affected by CVE-2018-20835?

Check whether you run tar-fs (npm) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2018-20835: tar-fs improper input validation in hardlink extraction

CVE-2018-20835 · Severity: low · CVSS 3 · Published 2019-05-01

tar-fs is a Node.js library used to extract and create tar archives. An attacker can craft a malicious tarball that, when extracted, overwrites arbitrary files on the system by exploiting how hardlinks are processed during extraction. This could allow an attacker to replace critical application files or configuration with malicious content.

Technologies: tar-fs (npm). Vendors: npm.

Quick answers

Is CVE-2018-20835 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2018-20835 being exploited in the wild.
How severe is CVE-2018-20835?: Low severity, with a CVSS score of 3, published 1 May 2019.
Which products and versions are affected?: tar-fs (npm) SEMVER:introduced=0,fixed=1.16.2.
Is there a fix for CVE-2018-20835?: Yes. tar-fs (npm): upgrade to 1.16.2 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2018-20835 attacked?: It is attacked over the network.
Am I affected by CVE-2018-20835?: Check whether you run tar-fs (npm) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

tar-fs (npm): upgrade to 1.16.2 or later
```
npm install tar-fs@1.16.2
```

Technical details

The vulnerability is an improper input validation issue (CWE-20) in tar-fs before version 1.16.2 affecting hardlink extraction. When extracting a tarball containing a hardlink to an existing file followed by a plain file with the same name, the library fails to properly validate that the hardlink target is within the extraction directory, allowing the hardlink to reference files outside the intended extraction path. An attacker can exploit this by crafting a specially constructed tarball and providing it to an application that uses tar-fs to extract archives. The fix, implemented in commit 06672828, restricts hardlink targets to be within the tar archive's contents by using path normalization.

Affected products

tar-fs tar-fs before 1.16.2

Identifiers

CVE-2018-20835
GHSA-x2mc-8fgj-3wmr

Timeline

2019-04-30: disclosed
2019-05-01: advisory
2019: patched: Fixed in version 1.16.2

References

https://github.com/mafintosh/tar-fs/commit/06672828e6fa29ac8551b1b6f36c852a9a3c58a2

This page as Markdown. Free to reuse under CC BY 4.0 with a link back.