CVE-2026-21264Network attack vector

Spoofing via undisclosed cross-site scripting flaw

Published Jan 22, 2026 · Updated Jan 22, 2026

Cross-site scripting in Microsoft Account allows remote attackers to spoof account content through a crafted network request. Microsoft has not disclosed the affected page, input field, or encoding operation that mishandles attacker-controlled data. Exploitation requires user interaction and can disclose or modify data presented in the victim's browser, without interrupting service.

CVSS severity9.3
Critical
EPSS probability0.39%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cross-site scripting in Microsoft Account allows remote attackers to spoof account content through a crafted network request. Microsoft has not disclosed the affected page, input field, or encoding operation that mishandles attacker-controlled data. Exploitation requires user interaction and can disclose or modify data presented in the victim's browser, without interrupting service.

The record

CVE
CVE-2026-21264
Published
Jan 22, 2026
Updated
Jan 22, 2026
Vendor
Microsoft
Product
Microsoft account
Classifications
CWE-79
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 22, 2026CVE publishedPublication date reported by the CVE source.
  2. Jan 22, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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

  1. Affected versionversion=-

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Microsoft · Microsoft accountversion=-

Published CVSS scores

9.3Microsoft CorporationCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N
6.1NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

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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