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

Published · last modified .

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.

EPSS exploit prediction

EPSS: 0.002 (15.3th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 15th percentile — 15.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-86813: held from 0.002 to 0.002.

EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: 0.000

Affected products

  • Metform

Weakness classification (CWE)

References

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.