CVE-2026-40587

CVE-2026-40587 is a medium-severity vulnerability with a CVSS 3.x base score of 6.5. 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-613.

Key facts

Description

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.

Frequently asked questions

What is 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.
How severe is CVE-2026-40587?
CVE-2026-40587 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires high privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.
Is CVE-2026-40587 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (15th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-40587?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-40587 have an EU (EUVD) identifier?
Yes. CVE-2026-40587 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-24203.
When was CVE-2026-40587 published?
CVE-2026-40587 was published on 2026-04-21 and last updated on 2026-06-17.

References

Other CWE-613 (Insufficient Session Expiration) vulnerabilities

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