CVE-2026-40587
Raw vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:NCVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.
Summary
CVE-2026-40587 is a medium-severity Insufficient Session Expiration (CWE-613) vulnerability. Its CVSS base score is 6.5 (Medium).
Operationally, exploitation aligns with the MITRE ATT&CK technique Browser Session Hijacking (T1185); ranked at the 15th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to AC-12 (Session Termination) — see the control section below for these in your framework.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-24203
Vulnerability Data
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…
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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.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
AC-12 directly requires automatic session termination after a defined period, structurally preventing reuse of expired session identifiers.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Credential lifecycle management directly includes enforcing session expiration to prevent reuse.
Authorization policy enforcement and review covers terminating stale sessions to limit access scope.
Authentication mechanisms can incorporate session timeout checks but do not inherently address expiration policy.