CVE-2021-4074: The WHMCS Bridge WordPress plugin is vulnerable to Stored Cross-Site Scripting via the cc_whmcs_bridge_url par

Q: How do I fix CVE-2021-4074?

whmcs bridge: upgrade to newer than 6.1. Exact commands for each OS are on this page.

Q: Is CVE-2021-4074 being exploited?

CVE-2021-4074 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2021-4074 affect?

CVE-2021-4074 affects whmcs bridge. Severity is medium (CVSS 6.4). 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 an

Q: How urgent is CVE-2021-4074?

Priority 34/100. No elevated risk signals yet.

Routine

MEDIUM 6.4UPGRADE

CVE-2021-4074 is a medium-severity flaw (CVSS 6.4) affecting whmcs bridge. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	6.4 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.6% (top 54%)
CISA exploited list	No
Weakness	CWE-79, CWE-862
Published	2022-01-18
Last modified	2026-06-17

Publisher (CNA): Wordfence · Vendor: i-plugins

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2022-01-18 17:15 UTCPublished CVE record published
2026-06-17 04:18 UTCUpdated Record last modified

i-plugins whmcs bridge UPGRADE

Affected: <= 6.1

Fixed in: newer than 6.1

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy whmcs-bridge || rpm -q whmcs-bridge || whmcs-bridge --version

2. UPGRADE to newer than 6.1 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade whmcs-bridge

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade whmcs-bridge

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2021-4074?

whmcs bridge: upgrade to newer than 6.1. Exact commands for each OS are on this page.

Is CVE-2021-4074 being exploited?

CVE-2021-4074 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2021-4074 affect?

CVE-2021-4074 affects whmcs bridge. Severity is medium (CVSS 6.4). 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 an

How urgent is CVE-2021-4074?

Priority 34/100. No elevated risk signals yet.

Software pages

WordPress vulnerabilities · PHP vulnerabilities

Related CVEs

CVE-2021-25112 MEDIUM 6.1 UPGRADE The WHMCS Bridge WordPress plugin before 6.4b does not sanitise and escape the error parameter before outputti

References

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