What is CVE-2025-55321?

CVE-2025-55321 is a critical-severity vulnerability in Microsoft Azure Monitor, classified under Cross-site Scripting. CVSS score: 9.3/10. Published 2025-10-09.

How severe is CVE-2025-55321?

Critical severity. CVSS v3 base score is 9.3 out of 10.

Is CVE-2025-55321 known to be exploited?

1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

XSS in Microsoft Azure Monitor

CVE-2025-55321

Improper neutralization of input during web page generation ('cross-site scripting') in Azure Monitor allows an unauthorized attacker to perform spoofing over a network.

Vulnerability class: XSS (Cross-Site Scripting)

EPSS: 0.001 (21.9th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 9.3 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N/E:U/RL:O/RC:C.

Affected products

Microsoft Azure Monitor

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

Public proof-of-concept exploits

fkie-cad/nvd-json-data-feeds

References

Azure Monitor Log Analytics Spoofing Vulnerability (vendor-advisory, patch)

Frequently asked questions

What is CVE-2025-55321?: CVE-2025-55321 is a critical-severity vulnerability in Microsoft Azure Monitor, classified under Cross-site Scripting. CVSS score: 9.3/10. Published 2025-10-09.
How severe is CVE-2025-55321?: Critical severity. CVSS v3 base score is 9.3 out of 10.
Is CVE-2025-55321 known to be exploited?: 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.