Vulnerability in Metform
CVE-2026-86813
The MetForm WordPress plugin before 4.1.9 does not properly neutralize newline characters in user-submitted values that are placed into notification email headers, allowing unauthenticated attackers to inject additional email headers, such as Bcc, into the emails the site sends when a submitted field value is configured to populate a header.
Vulnerability class: CRLF Injection
CVSS v3 metric
CVSS v3 base score 4.8 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N.
Affected products
- Unknown Metform
Weakness classification (CWE)
References
- contact@wpscan.com (technical-description, exploit, vdb-entry)
Frequently asked questions
- What is CVE-2026-86813?
- CVE-2026-86813 is a medium-severity vulnerability in Metform, classified under CRLF Injection. CVSS score: 4.8/10. Published 2026-09-11.
- How severe is CVE-2026-86813?
- Medium severity. CVSS v3 base score is 4.8 out of 10.