How severe is CVE-2026-42085?

CVE-2026-42085 has a CVSS 3.x base score of 4.3, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability none.

Is CVE-2026-42085 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (23rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-42085?

CVE-2026-42085 primarily affects Openc3 Cosmos. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2026-42085?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-42085 have an EU (EUVD) identifier?

Yes. CVE-2026-42085 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-27059.

When was CVE-2026-42085 published?

CVE-2026-42085 was published on 2026-05-04 and last updated on 2026-06-17.

CVE-2026-42085

CVE-2026-42085 is a medium-severity vulnerability in Openc3 Cosmos with a CVSS 3.x base score of 4.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-23.

Key facts

Severity: Medium (CVSS 3.x base score 4.3)
EPSS exploit prediction: 0% (23rd percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-27059
Weakness: CWE-23
Affected product: Openc3 Cosmos
Published: 2026-05-04
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is 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.
How severe is CVE-2026-42085?: CVE-2026-42085 has a CVSS 3.x base score of 4.3, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability none.
Is CVE-2026-42085 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (23rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-42085?: CVE-2026-42085 primarily affects Openc3 Cosmos. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2026-42085?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-42085 have an EU (EUVD) identifier?: Yes. CVE-2026-42085 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-27059.
When was CVE-2026-42085 published?: CVE-2026-42085 was published on 2026-05-04 and last updated on 2026-06-17.

References

Affected products (3)

cpe:2.3:a:openc3:cosmos:*:*:*:*:open_source:*:*:*
cpe:2.3:a:openc3:cosmos:7.0.0:rc1:*:*:open_source:*:*:*
cpe:2.3:a:openc3:cosmos:7.0.0:rc2:*:*:open_source:*:*:*

More vulnerabilities in Openc3 Cosmos

CVE-2025-28389 — Critical (CVSS 9.8): Weak password requirements in OpenC3 COSMOS v6.0.0 allow attackers to bypass authentication via a brute force attack.
CVE-2025-28388 — Critical (CVSS 9.8): OpenC3 COSMOS before v6.0.2 was discovered to contain hardcoded credentials for the Service Account.
CVE-2025-28386 — Critical (CVSS 9.8): A remote code execution (RCE) vulnerability in the Plugin Management component of OpenC3 COSMOS v6.0.0 allows attackers…
CVE-2026-42088 — Critical (CVSS 9.6): OpenC3 COSMOS provides the functionality needed to send commands to and receive data from one or more embedded systems.…
CVE-2026-42087 — Critical (CVSS 9.6): OpenC3 COSMOS provides the functionality needed to send commands to and receive data from one or more embedded systems.…
CVE-2025-28384 — Critical (CVSS 9.1): An issue in the /script-api/scripts/ endpoint of OpenC3 COSMOS before 6.1.0 allows attackers to execute a directory…

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