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CVE-2021-24159 - Contact Form 7 Plugin

CVE-2021-24159

Due to the lack of sanitization and lack of nonce protection on the custom CSS feature, an attacker could craft a request to inject malicious JavaScript on a site using the Contact Form 7 Style WordPress plugin through 3.1.9. If an attacker successfully tricked a site’s administrator into clicking a link or attachment, then the request could be sent and the CSS settings would be successfully updated to include malicious JavaScript.

CVE-2021-24159

HIGH CVSS 8.8 Published 2021-04-05 Updated 2024-11-21
AI Risk High (78/100) Active Exploit: No strong signal Published Exploit: No public exploit references Priority: P2 Urgent
Severity Band HIGH
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Affected Components 2
Reference Links 2
AI Risk Engine High (78/100)
Exploitability High
Active Exploitation No strong signal
Published Exploit Status No public exploit references

Threat Timeline

  1. 2021-04-05 CVE published and first recorded in the threat feed.
  2. 2024-11-21 Record updated with latest vulnerability metadata.
  3. 2026-04-10 AI technical context refreshed for mitigation and impact guidance.
  4. Now Monitoring for follow-up changes, linked references, and new related CVEs.

AI Context

Machine-generated threat intelligence

AI Updated 5 days ago

AI enriched 5 days ago (2026-04-10 20:43 UTC)

Technical Summary

Due to the lack of sanitization and lack of nonce protection on the custom CSS feature, an attacker could craft a request to inject malicious JavaScript on a site using the Contact Form 7 Style WordPress plugin through 3.1.9. If an attacker successfully tricked a site’s administrator into clicking a link or attachment, then the request could be sent and the CSS settings would be successfully updated to include malicious JavaScript.

Potential Impact

Severity is HIGH (CVSS 8.8). Depending on deployment context, affected components may be exposed to unauthorized actions or data integrity risk.

Exploitability Assessment

Exploitability is assessed as High based on severity and technical exposure profile.

Primary risk drivers: severity and technical exposure profile

Mitigation Recommendations

Validate affected product versions, prioritize patching, and monitor references for vendor remediation guidance. If immediate patching is not possible, apply compensating controls and limit exposure of vulnerable surfaces.

Detection & Monitoring

Track authentication anomalies, unexpected file writes, and suspicious plugin API activity around affected components.

Business Impact Lens

AI risk score 78/100 (High, High) with priority P2 Urgent. Prioritize remediation where affected components process customer data, admin sessions, or Internet-exposed workflows.

Affected Products

Contact Form 7 PLUGIN · contact-form-7 Affected: <= 3.1.9 Fixed version not specified
Through 3 PLUGIN · through-3 Affected range not specified Fixed version not specified
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