HappyForms: HTML injection in administrator notification emails
The HappyForms WordPress plugin before 1.26.15 does not sanitise or escape a user-controlled referral value before embedding it in the form notification email, allowing unauthenticated attackers to inject arbitrary HTML into the emails site administrators receive. Other endpoint, parameter, role or implementation details not named in this export are not established by this record. Affected versions: before 1.26.15.
- Component
- HappyForms
- Plugin slug
happyforms- Affected
- < 1.26.15
- Safe version
1.26.15- Published
- Oct 21, 2026
This CVE was published Oct 21, 2026 and is one of 8 known issues for this plugin.
Update, patch or deactivate.
The authoritative export identifies 1.26.15 as fixed. Update to the applicable fixed release or a later supported release. Validate the referral value and escape it in the HTML email context before composing administrator notifications.
A safe version is available, so updating to that version or later is the preferred remediation. If an immediate update is not practical, consider a targeted application patch or temporarily restricting the affected functionality.
Deactivate only when warranted by your risk profile, or when advised by your hosting provider in the limited circumstances where the vulnerability cannot otherwise be mitigated. If you’re unsure which action is appropriate, contact Fused or your hosting provider for guidance.
Technical description
The HappyForms WordPress plugin before 1.26.15 does not sanitise or escape a user-controlled referral value before embedding it in the form notification email, allowing unauthenticated attackers to inject arbitrary HTML into the emails site administrators receive.
CVE / CNA vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N