Path Traversal in Openc3 Cosmos

CVE-2026-42085

OpenC3 COSMOS provides the functionality needed to send commands to and receive data from one or more embedded systems. Prior to versions 6.10.5 and 7.0.0-rc3, OpenC3 COSMOS contains a design flaw in the save_tool_config() function that allows saving tool configuration files at arbitrary locations inside the shared /plugins directory tree by supplying crafted configuration filenames. Although the implementation sufficiently mitigates standard path traversal attacks, by canonicalizing filename to an absolute path, all plugins share this same root directory. That enables users to create arbitrary file structures and overwrite existing configuration files within the shared /plugins directory. This issue has been patched in versions 6.10.5 and 7.0.0-rc3.

Published · last modified .

CVSS v3 metric

CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N.

EPSS exploit prediction

EPSS: 0.003 (24.5th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 24th percentile — 24.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-42085: held from 0.003 to 0.003.

EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: 0.000

Affected products

  • Openc3 Cosmos — versions < 6.10.5, 7.0.0, >= 7.0.0.pre.rc1, < 7.0.0-rc3

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-42085?
CVE-2026-42085 is a medium-severity vulnerability in Openc3 Cosmos, classified under Relative Path Traversal. CVSS score: 4.3/10. Published 2026-05-04.
How severe is CVE-2026-42085?
Medium severity. CVSS v3 base score is 4.3 out of 10.