Summary
Impact: Spoofing. Microsoft rating: Important. Not known to be exploited — Exploitation Less Likely. Customer action: Required.
Details
How could an attacker exploit this vulnerability?
An attacker could send a specially crafted link to a user and persuade them to click it, with no authentication required. If a user with administrative privileges clicks the link, successful exploitation could allow the attacker to perform actions using that user's privileges, potentially allowing access to or modification of organizational data.
According to the CVSS metric, user interaction is required (UI:R). What interaction would the user have to do?
Exploitation of the vulnerability requires that a user to open a specially crafted link.
An attacker would have no way to force users to click the link. Instead, an attacker would have to convince users to click the link through social engineering.
According to the CVSS metric, a successful exploitation could lead to a scope change (S:C). What does this mean for this vulnerability?
The vulnerability is in the web server, but the malicious scripts execute in the victim’s browser on their machine.
Security updates
15.02.1748.055 — https://support.microsoft.com/help/5128896
15.02.1544.050 — https://support.microsoft.com/help/5128897
15.01.2507.077 — https://support.microsoft.com/help/5128898
15.02.2562.056 — https://support.microsoft.com/help/5128895
Vulnerabilities 1
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Critical 9.3
Microsoft Exchange Server Spoofing Vulnerability
Improper neutralization of input during web page generation ('cross-site scripting') in Microsoft Exchange Server allows an unauthorized attacker to perform spoofing over a network.
Revision history
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#1
Information published.
References
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CVE-2026-70279 Microsoft Exchange Server Spoofing Vulnerability - HTML
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-70279
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Microsoft Exploitability Index
https://www.microsoft.com/en-us/msrc/exploitability-index?rtc=1
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Microsoft Support Lifecycle
https://support.microsoft.com/lifecycle
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Common Vulnerability Scoring System
https://www.first.org/cvss