CVE-2026-21527

Exchange Server vulnerability

CVSS

6.5

EPSS

7.7%

EPSS pct

94th

Exploited

No known

User interface (ui) misrepresentation of critical information in Microsoft Exchange Server allows an unauthorized attacker to perform spoofing over a network.

Affected vendor

Microsoft

Affected product

Exchange Server

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

Weakness type (CWE)

CWE-345 — Insufficient Verification of Data Authenticity
CWE-451
CWE-1286

Published

2026-02-10

Risk analysis

Based on its CVSS vector, this vulnerability is exploitable over the network, low attack complexity, requiring no privileges, no user interaction. Successful exploitation leads to low impact to confidentiality, low impact to integrity.

Its EPSS score of 7.7% reflects a lower probability of exploitation activity in the wild over the next 30 days, placing it above 94% of all scored CVEs.

Check your external exposure to CVE-2026-21527

Confirm whether Microsoft Exchange Server is running on any internet-facing host or subdomain.
Match discovered service fingerprints against the version affected by CVE-2026-21527.
Prioritise remediation if the asset is public, business-critical, or near authentication/payment flows.

How ThreatPort helps with CVE-2026-21527

ThreatPort's external attack surface scanner checks your internet-facing assets — agentlessly, from the outside in — for the exposed services and versions that CVE-2026-21527 affects, then prioritises the finding by real risk using CISA KEV and FIRST.org EPSS.

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