CVE-2026-45503
Published: 09 June 2026
Summary
CVE-2026-45503 is a high-severity Improper Authorization (CWE-285) vulnerability in Microsoft Exchange Server. Its CVSS base score is 8.1 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 36.3th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-35679
Vulnerability details
Server-side request forgery (ssrf) in Microsoft Exchange Server allows an authorized attacker to disclose information over a network.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
SSRF in public-facing Exchange Server directly enables exploitation of the application for info disclosure.
Affected Assets
Mitigating Controls
Likely Mitigating Controls AI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Communications are authorized only through managed boundary devices and segmented subnetworks.
Documented procedures facilitate correct implementation and ongoing management of authorization decisions.
Periodic reviews identify and correct flaws in authorization decisions or enforcement.
The control's documentation requirement reduces improper authorization by ensuring only mission-justified actions bypass authentication.
Establishing permitted attributes and values, plus auditing changes, ensures authorization decisions are based on correctly managed policy data.
Explicitly mandates authorizing remote access types before permitting connections, directly mitigating improper authorization.
The control explicitly requires authorization of each wireless access type prior to permitting connections.
Mandating explicit authorization of mobile device connections reduces the risk of improper authorization decisions for system access.