CVE-2026-21527: microsoft exchange_server
CVSS: 6.5v3.1MediumAnalyzed
Published 10-02-2026Last modified 19-08-2026
Vulnerability summary
CVE-2026-21527 is a medium (CVSS 6.5) vulnerability in microsoft exchange_server. EPSS estimates a 8.26% chance of exploitation in the next 30 days, higher than 94.8% of scored vulnerabilities.
CVSS score
6.5/10
010
Medium · v3.1 (CVE.org)EPSS score
8.26%
0%100%
Low · +0.28 pp in 30 daysKEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded
Timeline
- 10-02-2026PublishedVulnerability first disclosed.
- 19-08-2026Last modifiedVulnerability information updated.
Description
User interface (ui) misrepresentation of critical information in Microsoft Exchange Server allows an unauthorized attacker to perform spoofing over a network.
CVSS metrics
2 scores · 2 sources · 1 versionMedium 6.5Preferred score · CVE.org (CNA)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N/E:U/RL:O/RC:CSourcesAll 2 agree
- NVDNIST6.5MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
EPSS trend
Probability
8.26%
Chance of exploitation in the next 30 days
Percentile
95%
Versus all other CVEs
30-day change
+0.28 pp
From 7.97% on 20-09-2026
20-09-202620-10-2026
EPSS score8.26%
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root cause- CWE-345Insufficient Verification of Data AuthenticityThe product does not sufficiently verify the origin or authenticity of data, in a way that causes it to accept invalid data.
- CWE-451User Interface (UI) Misrepresentation of Critical InformationThe user interface (UI) does not properly represent critical information to the user, allowing the information - or its source - to be obscured or spoofed. This is often a component in phishing attacks.
- CWE-1286Improper Validation of Syntactic Correctness of InputThe product receives input that is expected to be well-formed - i.e., to comply with a certain syntax - but it does not validate or incorrectly validates that the input complies with the syntax.
Affected systems
Microsoft6 products
- exchange_server2016:cumulative_update_23 | 2019:cumulative_update_14 | 2019:cumulative_update_15
- exchange_server_subscription_edition< 15.02.2562.037
- microsoft exchange server 2016 cumulative update 23≥ 15.01.0.0, < 15.01.2507.066
- microsoft exchange server 2019 cumulative update 14≥ 15.02.0.0, < 15.02.1544.039
- microsoft exchange server 2019 cumulative update 15≥ 15.02.0.0, < 15.02.1748.043
1 vendor · 6 products
