Security readout for executives and security teams
Plain-English summary
CVE-2021-4074 affects the WHMCS Bridge WordPress plugin through version 6.1. A logged-in low-privilege user, such as a subscriber, could store malicious script content in a plugin parameter. That script could later run in another user’s browser, creating account, content, or administrative-risk depending on who views it.
Executive priority
Treat this as a moderate-priority web application risk. It is not documented as actively exploited in the provided sources, but it can let ordinary authenticated users plant browser-executed code on affected WordPress sites.
Technical view
The issue combines stored cross-site scripting in the cc_whmcs_bridge_url parameter with missing authorization checks in cc_whmcs_bridge_add_admin. The CVSS 3.1 score is 6.4, with low attack complexity, required low privileges, changed scope, and limited confidentiality and integrity impact.
Likely exposure
Exposure is most likely on WordPress sites running WHMCS Bridge version 6.1 or earlier, especially where subscriber registration or low-privilege user accounts are enabled.
Exploitation context
The provided sources do not show CISA KEV listing or confirmed active exploitation. Exploitation requires an authenticated low-privilege account and abuses stored plugin data rather than unauthenticated network access.
Researcher notes
Evidence supports stored XSS plus missing authorization, but the bundle does not name a specific fixed version. Avoid assuming exploitation in the wild. Focus validation on version exposure, low-privilege account availability, and integrity of stored plugin settings.
Mitigation direction
- Inventory WordPress sites for WHMCS Bridge installations.
- Update WHMCS Bridge beyond affected versions if vendor guidance provides a fixed release.
- If no fixed release is available, evaluate disabling the plugin.
- Restrict creation and use of low-privilege WordPress accounts.
- Review plugin configuration for unexpected script-like content.
Validation and detection
- Confirm whether WHMCS Bridge is installed and at version 6.1 or earlier.
- Check WordPress user registration and subscriber account exposure.
- Review logs for low-privilege access to WHMCS Bridge admin paths.
- Inspect stored WHMCS Bridge settings for unauthorized changes.
- Confirm remediation through plugin inventory after update or removal.
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
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CWE-79: User-session and phishing behavior lookup
Client-side and session-facing weaknesses should be reviewed alongside initial-access and user-execution behaviors. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCWE-862: Authorization and privilege behavior lookup
Authorization weaknesses can support privilege escalation and valid-account review, depending on exploit path. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2021-4074 mapping review
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Open ATT&CK lookup- Severity
- Medium
- CVSS
- 6.4 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N3.12.7Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
6.4MediumVector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N
Source materials
- CVE List V5 sourceCVE List V5
- https://www.wordfence.com/vulnerability-advisories/#CVE-2021-4074CVE reference · x_refsource_MISC
- https://plugins.trac.wordpress.org/changeset?sfp_email=&sfph_mail=&reponame=&old=2653041%40whmcs-bridge&new=2653041%40whmcs-bridge&sfp_email=&sfph_mail=CVE reference · x_refsource_MISC
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.