Authentication bypass affecting Microsoft Exchange Server
A vulnerability affecting Microsoft Exchange Server would allow a malicious actor to elevate privileges on the affected system.
Description
Technical context and vulnerability details
Microsoft Exchange Server is an email and collaboration solution developed by Microsoft, widely deployed in enterprise environments for managing emails, calendars and contacts. This solution is affected by a vulnerability labeled CVE-2026-62911, which would allow an authenticated malicious actor, by replaying intercepted data exchanges, to bypass authentication mechanisms and elevate their privileges. It is classified as high with a severity score of 8.0 according to CVSS v3.1.
Potential Risks & Impact
Potential consequences upon exploitation
- Violation of data availability, confidentiality and integrity;
- Compromise of server and associated services;
Affected systems
Products, components and targeted versions
- Exchange 2016 CU23: versions prior to 15.1.2507.72;
- Exchange 2019 CU14: versions prior to 15.2.1544.43;
- Exchange 2019 CU15: versions prior to 15.2.1748.48;
- Exchange SE RTM: versions prior to 15.2.2562.45;
Recommended Remediations & Actions
Immediate actions and recommended mitigations
- Update Microsoft Exchange Server to patched versions:;
- 15.1.2507.72 (Exchange 2016 CU23);
- 15.2.1544.43 (Exchange 2019 CU14);
- 15.2.1748.48 (Exchange 2019 CU15);
- 15.2.2562.45 (Exchange SE RTM);
Sources & External Links
Vendor security advisories and documentation
Advisory Specifications
CSIRT Emergency Response
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