CVE-2026-21529Network attack vector

Authenticated spoofing via cross-site scripting

Published Feb 10, 2026 · Updated Feb 10, 2026

Cross-site scripting in Microsoft Azure HDInsight before 5.1 allows remote authenticated users to perform network-based spoofing. The flaw is in the Ambari browser UI, but Microsoft has not identified which UI path renders attacker-controlled input without neutralization. Exploitation requires low-privileged authorization and user interaction; Microsoft's vector reports service interruption rather than data access or modification.

CVSS severity5.7
Medium
EPSS probability0.65%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Cross-site scripting in Microsoft Azure HDInsight before 5.1 allows remote authenticated users to perform network-based spoofing. The flaw is in the Ambari browser UI, but Microsoft has not identified which UI path renders attacker-controlled input without neutralization. Exploitation requires low-privileged authorization and user interaction; Microsoft's vector reports service interruption rather than data access or modification.

The record

CVE
CVE-2026-21529
Published
Feb 10, 2026
Updated
Feb 10, 2026
Vendor
Microsoft
Product
Azure HDInsight
Classifications
CWE-79
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 10, 2026CVE publishedPublication date reported by the CVE source.
  2. Feb 10, 2026Record 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=1.0 <5.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Microsoft · Azure HDInsightversion=1.0 <5.1

Published CVSS scores

5.4NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
5.7Microsoft CorporationCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H
5.0Microsoft CorporationCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C

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

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

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo