CVE-2021-42943Public exploitNetwork attack vector

Stored XSS via unsanitized userid parameter

Published May 17, 2022 · Updated Aug 4, 2024

Stored cross-site scripting in IPPlan v4.92b allows remote attackers to inject arbitrary script via the userid parameter. The admin/usermanager.php handler stores attacker-controlled userid data and later renders it without adequate output encoding, causing script or HTML to execute in an administrator's browser. Exploitation requires access to the remote web interface and a victim or administrator to load the affected page; impact is unauthorized browser-side data access or actions within that session, not direct server code execution.

CVSS severity5.4
Medium
EPSS probability0.73%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored cross-site scripting in IPPlan v4.92b allows remote attackers to inject arbitrary script via the userid parameter. The admin/usermanager.php handler stores attacker-controlled userid data and later renders it without adequate output encoding, causing script or HTML to execute in an administrator's browser. Exploitation requires access to the remote web interface and a victim or administrator to load the affected page; impact is unauthorized browser-side data access or actions within that session, not direct server code execution.

The record

CVE
CVE-2021-42943
Published
May 17, 2022
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-79, T1189
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. May 17, 2022CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 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

5.4NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
3.5NVDAV: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.

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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 exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1189Drive-by Compromise

Public exploit references

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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