CVE-2026-21527 | Microsoft Exchange Server Spoofing Vulnerability

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

Published: 2026-02-10 Last update: 2026-02-11 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-21527 is rated Low Risk (32.1/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.06%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-21527

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-02-18 0.03% 0.06% +0.03%
2 2026-02-11 — 0.03% —

Full EPSS history (2 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-21527

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.5 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.
 3.9 2.5 [email protected]

Weakness enumeration for CVE-2026-21527

Affected software / configurations for CVE-2026-21527

Vendor Product Version Raw CPE
microsoft exchange_server < 15.02.2562.037 cpe:2.3:a:microsoft:exchange_server:*:*:*:*:subscription:*:*:*
microsoft exchange_server 2016 cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_23:*:*:*:*:*:*
microsoft exchange_server 2019 cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_14:*:*:*:*:*:*
microsoft exchange_server 2019 cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_15:*:*:*:*:*:*

References for CVE-2026-21527

cvelogic Threat Intelligence