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WordPress plugin

WHMCS Bridge <= 6.1 Subscriber+ Stored Cross-Site Scripting

CVE-2021-4074Published · Updated

Action summary

Affected: ≤6.1Update to 6.3 or newer

All remediation steps
Watch plugin
Severity
Medium6.4
CVSS
6.4
CVSS 3.1 · CNA (Wordfence)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N
What does this vector mean?
AV:N Attack vector
Network
AC:L Attack complexity
Low
PR:L Privileges required
Low
UI:N User interaction
None
S:C Scope
Changed
C:L Confidentiality
Low
I:L Integrity
Low
A:N Availability
None
Weakness
CWE-79 Cross-Site Scripting
Required access
Unknown
Exploit prediction (EPSS)
No score
CISA KEV
Not listed
On this page8

Am I affected?

WHMCS Bridge whmcs-bridge

  1. Affected≤ 6.1
  2. Patched in6.3

Update to 6.3 or newer.

You are affected if you run ≤ 6.1. Version 6.3 and later are not affected by this issue.

  • Check your version: in wp-admin go to Plugins → Installed Plugins and read the version under WHMCS Bridge.
  • No admin access? Run a passive check of your site. It reads public files only.

What to do

  1. Update to version 6.3, or a newer patched version
  2. Rotate administrator passwords and application secrets if the site ran a vulnerable version while publicly reachable.
  3. Watch WHMCS Bridge to get an email when the next vulnerability is published.

Advisory

Source description from Wordfence Intelligence, credited to Kazuto Kokonoe.

The WHMCS Bridge WordPress plugin is vulnerable to Stored Cross-Site Scripting via the cc_whmcs_bridge_url parameter found in the ~/whmcs-bridge/bridge_cp.php file which allows attackers to inject arbitrary web scripts, in versions up to and including 6.1. Due to missing authorization checks on the cc_whmcs_bridge_add_admin function, low-level authenticated users such as subscribers can exploit this vulnerability.

Exploits & references

Proof-of-concept & detection

No public proof-of-concept or detection template is known for this vulnerability.

Advisories & patches

More in WHMCS Bridge

All 3
More vulnerabilities in WHMCS Bridge
SeverityVulnerabilityCVEPublished
High8.8Unauthenticated Arbitrary File Upload via 'ccce' Parameter
≤6.9No patch available
CVE-2026-14489
Medium6.1Reflected Cross-Site Scripting
≤6.3Update to 6.4b
CVE-2021-25112

Same weakness (Cross-Site Scripting)

All Cross-Site Scripting
Other Cross-Site Scripting vulnerabilities
SeverityVulnerabilityCVEPublished
High7.2Unauthenticated Stored Cross-Site Scripting via Comment User-Agent Header
EZ SQL Reports Shortcode Widget and DB Backup≤5.25.25Update to 5.26.45
CVE-2026-120688
Critical9.8Unauthenticated Arbitrary File Upload via File Upload via Public Form Submission
Chatterbug Forms – Fast, Flexible WordPress Form Builder≤1.0.2Update to 1.1
CVE-2026-125055
Critical9.8Unauthenticated PHP Object Injection to Remote Code Execution via 'form' Parameter
ELEX WordPress HelpDesk & Customer Ticketing System≤3.3.9Update to 3.4.0
CVE-2026-119077
Medium5.3Unauthenticated Sensitive Information Exposure in 'search' Parameter
Customer Reviews for WooCommerce≤5.127.0Update to 5.128.0
CVE-2026-121518

Timeline

  1. CVE published

    Severity medium, CVSS 6.4

  2. Record last updated

Sources & licenses

Wordfence record
Vulnerability data
Wordfence Intelligence. [object Object] Licensed under the CC BY-SA 4.0.
CVE® identifiers
[object Object]. Used under the CVE Program. CVE® is a registered trademark of The MITRE Corporation.
CVSS / CWE
National Vulnerability Database (NVD), shown unmodified. This product uses the NVD API but is not endorsed or certified by the NVD.
VulnCrest content
Summary, remediation guidance and page layout © VulnCrest. Not sourced from NVD.

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