MetForm < 4.1.9 - Unauthenticated Email Header Injection via Notification Reply-To (CVE-2026-86813) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-86813

MetForm < 4.1.9 - Unauthenticated Email Header Injection via Notification Reply-To

Answer in brief

CVE-2026-86813 records a Unknown severity vulnerability in MetForm < 4.1.9 - Unauthenticated Email Header Injection via Notification Reply-To. The current sources do not mark it as known exploited. The current feed maps Unknown/MetForm (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 11, 2026Updated Sep 11, 2026Source checked Sep 11, 2026First seen by HOL Sep 11, 2026Material review Sep 11, 2026

Upstream Advisory

Key facts

Risk: Unknown severitySource severity not reported
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Available

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Unknown/MetForm (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Unknown/MetFormgeneric	>=0 <4.1.9	4.1.9

Recommended response

Check inventory. Check lockfiles and deployed manifests for Unknown/MetForm.
Review the reported fix. Update Unknown/MetForm to 4.1.9 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 11, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 11, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 11, 2026

Sources and claim methodology

Source referencewpscan.com

Upstream source 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.

Quoted source text, attributed separately from HOL analysis.