Microsoft Exchange CVE-2020-0688
HIGHVulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A07:2021 - Identification and Authentication Failures
ASVS 5.0
V2 - Authentication Authentication mechanism strength, credential management
MITRE ATT&CK
2 techniques across 2 tactics: Defense Evasion, Initial Access The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. |
| Impact | Critical risk (CVSS 8.8, EPSS 94.4%). Any user with a valid mailbox can escalate to SYSTEM on the Exchange server. This was widely exploited in 2020, including by APT groups for initial persistence on Exchange infrastructure. |
| Exploit ScenarioDerived | An attacker with stolen or phished email credentials crafts a malicious ViewState payload using the static Exchange keys, submits it to the ECP endpoint, and achieves code execution as SYSTEM on the Exchange server. From there, they access all mailboxes, extract the AD database, or deploy additional backdoors. |
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Alert meAnalysisAIv1 – Mar 26, 2026
Microsoft Exchange Server contains a remote code execution vulnerability caused by static cryptographic keys used in the Exchange Control Panel, allowing authenticated attackers to execute code as SYSTEM.
Earlier versions of this analysis (1)
A remote code execution vulnerability in Microsoft Exchange arises from the use of static/default cryptographic keys for ViewState validation in the Exchange Control Panel (ECP), enabling authenticated users to achieve SYSTEM-level code execution.
RemediationAI
Apply Microsoft security update. Regenerate Exchange's cryptographic keys. Monitor for anomalous ECP requests. Implement mailbox audit logging.
Affected ProductsAI
Microsoft Exchange Server (affected versions)
Affects your stack
Find out whether the stacks and servers you run are on an affected version.
Checking this CVE against your own stacks and servers is part of the Basic plan and up.
Technical ContextAI · show details
The CWE-287 authentication flaw stems from Exchange using a static validationKey and decryptionKey in web.config for ViewState MAC validation. An authenticated attacker (any mailbox user) can craft a serialized ViewState payload, sign it with the known static key, and send it to ECP for deserialization and code execution as SYSTEM.
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- Exploit and PoC references, threat intelligence from 22 sources
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Severity by source
AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Primary rating from NVD · only source for this CVE.
CVSS VectorNVD
Lifecycle Timeline
4DescriptionCVE.org
A remote code execution vulnerability exists in Microsoft Exchange software when the software fails to properly handle objects in memory, aka 'Microsoft Exchange Memory Corruption Vulnerability'.
Executive ViewAI
CVE-2020-0688 presents significant security risk, a improper authentication vulnerability rated CVSS 8.8. Attackers could bypass security controls to gain unauthorized access to protected resources and sensitive data. This vulnerability is actively exploited in the wild (KEV-listed) and requires immediate remediation. A patch is available and should be applied as part of regular vulnerability management.
Apply vendor patch. If immediate patching is not feasible: (1) Implement network-level access controls; (2) Enable MFA where possible; (3) Monitor authentication logs for anomalous access.
Threat Intelligence Overview
NVD
CVE.org
CISA KEV
EPSS
Exploit-DB
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
GitHub PoC