CVE-2021-36911Network attack vector

Editor-level stored script execution

Published Dec 10, 2021 · Updated Apr 28, 2026

Stored XSS in @rex1989 Comment Engine Pro 1.0 and earlier allows remote authenticated users to execute script in a visitor's browser. The affected input, storage path, rendering sink, and faulty neutralization operation have not been publicly identified. Editor or higher privileges are required to store the payload, and a separate visitor must render the affected content for script execution.

CVSS severity5.4
Medium
EPSS probability0.55%
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 @rex1989 Comment Engine Pro 1.0 and earlier allows remote authenticated users to execute script in a visitor's browser. The affected input, storage path, rendering sink, and faulty neutralization operation have not been publicly identified. Editor or higher privileges are required to store the payload, and a separate visitor must render the affected content for script execution.

The record

CVE
CVE-2021-36911
Published
Dec 10, 2021
Updated
Apr 28, 2026
Vendor
@rex1989
Product
Comment Engine Pro
Classifications
CWE-79, T1059.007
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Dec 10, 2021CVE publishedPublication date reported by the CVE source.
  2. Apr 28, 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 <=1.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

@rex1989 · Comment Engine Proversion=<= 1.0 <=1.0

Published CVSS scores

5.4NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
4.8PatchstackCVSS:3.1/AV:N/AC:L/PR:H/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.

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')
T1059.007Command and Scripting Interpreter: JavaScript

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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