CVE-2025-55321Network attack vector

Unauthenticated browser-session spoofing

Published Oct 9, 2025 · Updated Oct 9, 2025

Cross-site scripting in Microsoft Azure Monitor allows remote attackers to perform spoofing through a victim's browser. Microsoft has not disclosed the affected interface, attacker-controlled input, or operation that places that input into generated web content without neutralization. Exploitation requires a user to interact with attacker-supplied content; successful script execution exposes or changes data available to that browser session.

CVSS severity9.3
Critical
EPSS probability0.44%
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 Azure Monitor allows remote attackers to perform spoofing through a victim's browser. Microsoft has not disclosed the affected interface, attacker-controlled input, or operation that places that input into generated web content without neutralization. Exploitation requires a user to interact with attacker-supplied content; successful script execution exposes or changes data available to that browser session.

The record

CVE
CVE-2025-55321
Published
Oct 9, 2025
Updated
Oct 9, 2025
Vendor
Microsoft
Product
Azure Monitor
Classifications
CWE-79, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 9, 2025CVE publishedPublication date reported by the CVE source.
  2. Oct 9, 2025Record 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=N/A

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Microsoft · Azure Monitorversion=N/A

Published CVSS scores

9.3Microsoft CorporationCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N
5.4NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:L/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')
T1203Exploitation for Client Execution

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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