Cyber Resilience

CVE-2025-53782

Auth Bypass in Microsoft Exchange Server 2016 … 2019

Published
14 October 2025
Modified
15 June 2026
Patch / advisory
CVSS Score v3.1 8.4
Click a component to see what it means
Raw vectorCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.0033 26th percentile
Risk Priority 61 floored blend · peak EPSS

Summary

CVE-2025-53782 is a high-severity Incorrect Implementation of Authentication Algorithm (CWE-303) vulnerability in Microsoft Exchange Server. Its CVSS base score is 8.4 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique External Remote Services (T1133); ranked at the 26th 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 SA-11 (Developer Testing and Evaluation) and SA-15 (Development Process, Standards, and Tools) — see the control section below for these in your framework.

OWASP Top 10 for Web (2025)

EU & UK References

Vulnerability Data

Incorrect implementation of authentication algorithm in Microsoft Exchange Server allows an unauthorized attacker to elevate privileges locally.

CWE(s)

Related Threats

MITRE ATT&CK Enterprise Techniques

T1133 External Remote Services Persistence
Adversaries may leverage external-facing remote services to initially access and/or persist within a network.
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2026-45502Same product: Microsoft Exchange Server
CVE-2026-45504Same product: Microsoft Exchange Server
CVE-2025-25007Same product: Microsoft Exchange Server
CVE-2026-55009Same product: Microsoft Exchange Server
CVE-2025-53786Same product: Microsoft Exchange Server
CVE-2025-25006Same product: Microsoft Exchange Server
CVE-2025-59249Same product: Microsoft Exchange Server
CVE-2026-55008Same product: Microsoft Exchange Server
CVE-2026-45500Same product: Microsoft Exchange Server
CVE-2025-25005Same product: Microsoft Exchange Server

Affected Assets

microsoft
exchange server
2016, 2019
microsoft
exchange server subscription edition
≤ 15.02.2562.029

Mitigating Controls

Mitigating Controls (NIST 800-53 r5) AI

Developer testing and evaluation at post-design stages directly uncovers incorrect implementations of required authentication algorithms.

Requiring documented development processes, standards, and tools reduces the chance that an established authentication algorithm is coded incorrectly.

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.

PR.PS-06 mostly match
prevents

Secure SDLC practices directly require correct implementation of authentication algorithms.

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.

degrades

Secure authentication control directly requires correct implementation of authentication algorithms.

finds

Security testing can detect flawed authentication implementations but does not prevent them by itself.

degrades

Cryptography control addresses proper use of authentication algorithms but is broader than authentication alone.

prevents

Secure development lifecycle includes verification steps that can catch incorrect authentication implementations.

prevents

Application security requirements can specify correct authentication algorithm use but do not guarantee correct implementation.

prevents

Secure coding practices reduce the likelihood of incorrect authentication algorithm implementation.

References