Quick answers
- Is CVE-2026-39245 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-39245 being exploited in the wild.
- How severe is CVE-2026-39245?
- Informational severity, with a CVSS score of 9.8, published 9 July 2026.
- Which products and versions are affected?
- Kevin Mårtensson Decompress < 4.2.2.
- Is there a fix for CVE-2026-39245?
- No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
- How is CVE-2026-39245 attacked?
- It is attacked over the network, in a software library.
- Am I affected by CVE-2026-39245?
- Check whether you run Kevin Mårtensson Decompress 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.
Technical details
The vulnerability exists in index.js within the safeMakeDir function and extraction path validation logic. The library uses String.indexOf() to verify if a resolved path is within the output directory but fails to enforce a path separator boundary. For example, a check for '/tmp/app' would incorrectly validate '/tmp/app_config' because the latter starts with the same string. When combined with unvalidated symlink creation, a remote attacker can bypass intended directory restrictions to perform arbitrary file writes. This is a bypass of the previous fix for CVE-2020-12265. The issue is resolved in version 4.2.2 by ensuring a path separator is appended during the containment check.
Affected products
- kevva decompress < 4.2.2
Timeline
- 2026-07-04: disclosed: Issue reported on GitHub by devploit
- 2026-07-09: advisory: CVE-2026-39245 published