CVE-2021-36830Network attack vector

Stored XSS via unsanitized settings

Published Sep 30, 2022 · Updated Apr 28, 2026

Cross-site scripting in Comment Guestbook 0.8.0 and earlier allows remote authenticated users to execute script via crafted settings. The plugin fails to sanitize and escape some administrative settings, permitting stored script injection even when WordPress unfiltered_html is disallowed. An administrator-level account and a victim who loads affected guestbook or administrative content are required, with confidentiality and integrity impact but no service interruption reported.

CVSS severity4.8
Medium
EPSS probability0.44%
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 Comment Guestbook 0.8.0 and earlier allows remote authenticated users to execute script via crafted settings. The plugin fails to sanitize and escape some administrative settings, permitting stored script injection even when WordPress unfiltered_html is disallowed. An administrator-level account and a victim who loads affected guestbook or administrative content are required, with confidentiality and integrity impact but no service interruption reported.

The record

CVE
CVE-2021-36830
Published
Sep 30, 2022
Updated
Apr 28, 2026
Vendor
mibuthu
Product
Comment Guestbook
Classifications
CWE-79, T1059.007
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. Sep 30, 2022CVE 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

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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=<= 0.8.0 <=0.8.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesadmin

What is affected?

mibuthu · Comment Guestbookversion=<= 0.8.0 <=0.8.0

Published CVSS scores

4.8[email protected]CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N
4.8[email protected]CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Cross-site Scripting (XSS)
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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