The flaw lies in the session management mechanism of blueprintUE. When a user changes their password or completes a reset through the web interface, the current session store continues to reference the existing session tokens. Consequently, any actor who has already hijacked a session remains fully authenticated until that session is naturally discarded, typically after 24 hours or when the browser is closed. This allows repeated unauthorized access to the user's account after the legitimate owner has taken remedial action, effectively turning temporary credential theft into persistent state. The weakness is classified as CWE-613, indicating that session invalidation is omitted after a password change.

All installations of blueprintUE self-hosted edition older than version 4.2.0 are impacted; the vulnerability is fixed in 4.2.0.

The CVSS score is 6.5, indicating a medium severity that could lead to persistent account compromise. EPSS is not reported, and the vulnerability is not listed in CISA's KEV catalog. The attack vector is inferred to be remote, requiring an attacker to possess a valid session cookie, which could be obtained through typical credential theft or other session hijacking techniques. Once a session is hijacked, the vulnerability allows it to remain active indefinitely, raising the risk of long-term unauthorized access. Even with session timeout policies, the window of exposure expands to the full GC lifetime or browser lifetime.