CVE-2026-96940
Microsoft Exchange Server 2016 … 2019
Raw vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HCVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.
Summary
CVE-2026-96940 is a high-severity Weak Authentication (CWE-1390) vulnerability in Microsoft Exchange Server. Its CVSS base score is 8.8 (High).
Operationally, ranked at the 41th 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-3 (Access Enforcement) and IA-12 (Identity Proofing) — see the control section below for these in your framework.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-91771
Vulnerability Data
Weak authentication in Microsoft Exchange Server allows an authorized attacker to elevate privileges over a network.
- CWE(s)
Related Threats
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Enforces access decisions based on authenticated identities, making weak authentication less exploitable.
Requires identity proofing at appropriate assurance levels before granting accounts, directly addressing insufficient proof of identity.
Requires unique identification and authentication of users, directly stopping weak mechanisms from being used.
Requires device identification and authentication before establishing connections.
Mandates proper authenticator issuance, management, and strength to ensure claimed identities are verified.
Extends strong identification and authentication requirements to non-organizational users.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
A.5.17 directly mandates non-guessable unique secrets, identity verification before issuance, secure transmission, immediate default changes, strong password enforcement, no reuse, and protected storage/transmission, which stops exploitation of most insufficient-proof cases in CWE-1390; the bounded remainder is non-password mechanisms (e.g. biometrics, certificates) or flawed protocol-level proof not covered by these password-centric rules.
A.8.5 directly mandates choosing sufficiently strong authentication techniques (including MFA, biometrics with fallback, brute-force protection, secure log-on procedures) that prove claimed identity, which stops exploitation of insufficient proof for most but not all cases in CWE-1390 (e.g. residual protocol-level or implementation-specific flaws remain possible).
Hardening callouts derived
DISA STIG baselines are authored against specific weaknesses. Where this CVE cites a broad weakness class, the mapping is not asserted at that abstraction (owner ruling, 2026-09-25: grade only at Base and below), so no rule is shown here rather than a rule shown against the wrong grain.