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CVE-2026-42084 (openc3): OpenC3 COSMOS - Hijacked session token can be used to reset password for persistence

OpenC3 COSMOS - Hijacked session token can be used to reset password for persistence

Published: April 22, 2026

SECURITY IDENTIFIERS

GEM

openc3

SEVERITY

CVSS v3.x: 8.1 (High)

PATCHED VERSIONS

~> 6.10.5 >= 7.0.0-rc3

DESCRIPTION

Summary

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.

Details

The design flaw in authentication model (authentication.rb) allows for interchangeable use of password and session tokens for user authentication As old tokens are not revoked upon password reset, an attacker who has obtained a valid session token can continue to authenticate and change the account’s password even after the victim resets it, thereby maintaining persistent control over the compromised account.

Impact

Persistence of an attacker who obtained valid session token and preventing legitimate users from account access.

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