CVE-2026-8420Public exploitNetwork attack vector

Stored XSS via forged settings update

Published May 20, 2026 · Updated May 20, 2026

Cross-site request forgery in BLOGCHAT Chat System 1.3.6.3 and earlier allows remote attackers to inject stored scripts through settings. The settings-handling code in wp-blogchat-widget.php accepts attacker-supplied configuration values without validating a WordPress nonce. An administrator must be signed in and induced to submit the forged request; the saved script then runs in the site context for later visitors.

CVSS severity6.1
Medium
EPSS probability0.17%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cross-site request forgery in BLOGCHAT Chat System 1.3.6.3 and earlier allows remote attackers to inject stored scripts through settings. The settings-handling code in wp-blogchat-widget.php accepts attacker-supplied configuration values without validating a WordPress nonce. An administrator must be signed in and induced to submit the forged request; the saved script then runs in the site context for later visitors.

The record

CVE
CVE-2026-8420
Published
May 20, 2026
Updated
May 20, 2026
Vendor
Fastcat Software
Product
BLOGCHAT Chat System
Classifications
CWE-352, T1204.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 20, 2026CVE publishedPublication date reported by the CVE source.
  2. May 20, 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 <=1.3.6.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Fastcat Software · BLOGCHAT Chat Systemversion=0 <=1.3.6.3

Published CVSS scores

6.1GitHub Advisory DatabaseCVSS:3.1/AV:N/AC:L/PR:N/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.

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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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-352Cross-Site Request Forgery (CSRF)
T1204.001Malicious Link

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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