CVE-2023-51630Network attack vector

Authentication bypass via error page script injection

Published Feb 8, 2024 · Updated Aug 2, 2024

Cross-site scripting in Paessler PRTG Network Monitor 23.4.90.1299 and earlier allows remote attackers to bypass authentication. The error.htm handler places the user-controlled htmclass parameter into the web console without proper validation, enabling arbitrary script injection. Exploitation requires a PRTG user with an active session to open a malicious link, allowing the injected script to act within that user's session.

CVSS severity8.8
High
EPSS probability1.75%
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 Paessler PRTG Network Monitor 23.4.90.1299 and earlier allows remote attackers to bypass authentication. The error.htm handler places the user-controlled htmclass parameter into the web console without proper validation, enabling arbitrary script injection. Exploitation requires a PRTG user with an active session to open a malicious link, allowing the injected script to act within that user's session.

The record

CVE
CVE-2023-51630
Published
Feb 8, 2024
Updated
Aug 2, 2024
Vendor
Paessler
Product
PRTG Network Monitor
Classifications
CWE-79, T1059.007, T1204.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 8, 2024CVE publishedPublication date reported by the CVE source.
  2. Aug 2, 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?

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

  1. Affected versionversion=23.2.84.1566

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Paessler · PRTG Network Monitorversion=23.2.84.1566

Published CVSS scores

6.1NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
8.8Zero Day InitiativeCVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

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')
T1059.007JavaScript/JScript
T1204.001Malicious Link

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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