Raw vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:NSummary
CVE-2026-42085 is a medium-severity Relative Path Traversal (CWE-23) vulnerability in Openc3 Cosmos. Its CVSS base score is 4.3 (Medium).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 24th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
The strongest mitigations our analysis identified map to SI-10 (Information Input Validation) and AC-3 (Access Enforcement) — see the control section below for these in your framework.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-27059
Vulnerability Data
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…
more
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.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
—
—
—
V5.3.2
Mitigating Controls (NIST 800-53 r5) AI
Explicit validation of path inputs stops .. sequences from ever being interpreted by the file system.
Access enforcement directly blocks unauthorized file reads/writes that result from unresolved .. sequences.
Information-flow rules can be configured to reject traversals that would move data outside an approved directory boundary.
Least privilege reduces the set of reachable files even when a traversal succeeds.
Secure-engineering principles require safe pathname construction and input neutralization before any file operation.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure SDLC practices directly require input validation and path sanitization that prevent relative traversal.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Security testing in development catches path traversal via static/dynamic analysis, but does not itself implement the fix.
Secure development lifecycle mandates input validation and path-handling controls that directly prevent relative path traversal.
Application security requirements explicitly call for controls against path traversal and other injection flaws.
Secure architecture principles include directory isolation and canonicalization, reducing but not eliminating traversal risk.
Secure coding standards require neutralizing path traversal sequences, directly addressing CWE-23.
Information access restriction limits which files can be reached, mitigating impact but not preventing the traversal flaw.