CVE-2021-24085Network attack vector

Authenticated UI spoofing via certificate-derived CSRF token

Published Feb 25, 2021 · Updated Aug 3, 2024

Spoofing in Microsoft Exchange Server 2016 CU18–CU19 and 2019 CU7–CU8 allows remote authenticated users to alter displayed content. A certificate-file disclosure supplies material from which Exchange generates a CSRF token; Microsoft has not disclosed the affected endpoint or code operation. Exploitation requires low-privilege authentication and victim interaction, and can alter content presented in another security context.

CVSS severity6.5
Medium
EPSS probability4.63%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Spoofing in Microsoft Exchange Server 2016 CU18–CU19 and 2019 CU7–CU8 allows remote authenticated users to alter displayed content. A certificate-file disclosure supplies material from which Exchange generates a CSRF token; Microsoft has not disclosed the affected endpoint or code operation. Exploitation requires low-privilege authentication and victim interaction, and can alter content presented in another security context.

The record

CVE
CVE-2021-24085
Published
Feb 25, 2021
Updated
Aug 3, 2024
Vendor
Microsoft
Product
Microsoft Exchange Server 2016 Cumulative Update 18
Classifications
Unavailable
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 25, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=15.01.0 <publication

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Microsoft · Microsoft Exchange Server 2016 Cumulative Update 18version=15.01.0 <publication
Microsoft · Microsoft Exchange Server 2016 Cumulative Update 19version=15.01.0 <publication
Microsoft · Microsoft Exchange Server 2019 Cumulative Update 8version=15.02.0 <publication
Microsoft · Microsoft Exchange Server 2019 Cumulative Update 7version=15.02.0 <publication

Published CVSS scores

6.0NIST NVDAV:N/AC:M/Au:S/C:P/I:P/A:P
6.5Microsoft CorporationCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:L
5.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

No sourced classifications are available.

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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