Vulnerability in Blueprintue Blueprintue-Self-Hosted-Edition

CVE-2026-40587

blueprintUE is a tool to help Unreal Engine developers. Prior to 4.2.0, when a user changes their password via the profile edit page, or when a password reset is completed via the reset link, neither operation invalidates existing authenticated sessions for that user. A server-side session store associates userID → session; the current password change/reset flow updates only the password column in the users table and does not destroy or mark invalid any active sessions. As a result, an attacker who has already compromised a session retains full access to the account indefinitely — even after the legitimate user has detected the intrusion and changed their password — until the session's natural expiry time (configured as SESSION_GC_MAXLIFETIME, defaulting to 86400 seconds / 24 hours, with SESSION_LIFETIME=0 meaning persistent until browser close or GC, whichever is later). This vulnerability is fixed in 4.2.0.

Published · last modified .

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N.

EPSS exploit prediction

EPSS: 0.004 (34.0th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 34th percentile — 34.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-40587: held from 0.002 to 0.004.

EPSS over last 30 days · oldest: 0.002 · newest: 0.004 · change: +0.002

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-40587?
CVE-2026-40587 is a medium-severity vulnerability in Blueprintue Blueprintue-Self-Hosted-Edition, classified under Insufficient Session Expiration. CVSS score: 6.5/10. Published 2026-04-21.
How severe is CVE-2026-40587?
Medium severity. CVSS v3 base score is 6.5 out of 10.