CVE-2026-86813 MetForm < 4.1.9 - Unauthenticated Email Header Injection via Notification Reply-To
Unauthenticated attackers can inject email headers like Bcc into MetForm notifications if field values populate headers, potentially exposing recipients or bypassing filters.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-86813?
CVE-2026-86813 is a medium-severity vulnerability in Unknown MetForm, published on 11 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-93
Which versions are affected by CVE-2026-86813?
How do I fix CVE-2026-86813?
No fix has been published for CVE-2026-86813 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-86813 being exploited?
There is no known exploitation of CVE-2026-86813 in the wild and no public exploit code.
Sources
Also known as GHSA-687m-wfrp-8mxf.