CVE-2021-25935Network attack vector

Stored XSS via unescaped foreign-source UI messages

Published May 25, 2021 · Updated Aug 3, 2024

Stored XSS in OpenNMS Horizon 17.0.0-1 through 27.1.0-1 allows remote authenticated users to inject scripts through foreign-source. The requisition add() path permits a crafted foreign-source value to bypass its regex, stores it, and inserts it into UI messages without HTML escaping. OpenNMS Meridian 2015.1.0-1 through 2019.1.18-1 and 2020.1.0-1 through 2020.1.7-1 is also affected; execution requires another user to view the affected requisition interface, where the script runs in that user's browser context.

CVSS severity5.4
Medium
EPSS probability0.91%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored XSS in OpenNMS Horizon 17.0.0-1 through 27.1.0-1 allows remote authenticated users to inject scripts through foreign-source. The requisition add() path permits a crafted foreign-source value to bypass its regex, stores it, and inserts it into UI messages without HTML escaping. OpenNMS Meridian 2015.1.0-1 through 2019.1.18-1 and 2020.1.0-1 through 2020.1.7-1 is also affected; execution requires another user to view the affected requisition interface, where the script runs in that user's browser context.

The record

CVE
CVE-2021-25935
Published
May 25, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-79, T1059.007
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. May 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

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

5.4NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
3.5NIST NVDAV:N/AC:M/Au:S/C:N/I:P/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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1059.007JavaScript/JScript

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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