Medium severity · published Sep 11, 2026
CVE-2026-86813
MetForm < 4.1.9 - Unauthenticated Email Header Injection via Notification Reply-To
4.8
CVSS
0.2%
EPSS
No
On KEV
Description
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.
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
Attack vector
Network
Complexity
High
Privileges
None
User interaction
None
Confidentiality
Low
Integrity
Low
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 16% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
ME
MetForm ·
before 4.1.9 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-86813
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-86813
wpscan.com
https://wpscan.com/vulnerability/afda2a26-b965-42cb-85a8-4a4d83ec026e/
More from MetForm
5.4
CVE-2026-86833
MetForm < 4.3.1 - Unauthenticated HTML Injection in Notification Emails via Field Shortcodes
5.3
CVE-2026-86832
MetForm < 4.3.1 - Unauthenticated Form Entry Data Disclosure via REST API
3.7
CVE-2026-86834
MetForm 2.2.1 - 4.3.0 - Unauthenticated Debug File Disclosure via HubSpot Forms Integration