---
id: "CVE-2026-115479"
kind: "vulnerability"
aliases: ["CVE-2026-115479"]
title: "baserCMS: public mail form lets visitors send auto-replies to many addresses"
severity: "medium"
cvss: 5.3
epss: 0.00412
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["basercms", "mail", "package", "php", "self-hosted"]
not_affected_if: ["default-config", "valid-email-enabled"]
published_at: "2026-10-23T14:17:52+00:00"
first_seen_at: "2026-10-23T21:57:34+00:00"
updated_at: "2026-10-25T12:38:50+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-115479", "first_seen_at": "2026-10-23T21:57:34+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-115479", "first_seen_at": "2026-10-25T12:38:50+00:00"}]
---

# baserCMS: public mail form lets visitors send auto-replies to many addresses

A visitor can enter a comma-separated list of addresses in a public form's email field, and baserCMS sends the auto-reply to all of them from the site's sender address. An attacker can use the site to deliver unsolicited mail to third parties.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the baserCMS version: `5.2.5` through `5.3.1` and `5.4.0` through `5.4.1` are affected.
- Check whether forms with an email-type field have the VALID_EMAIL server-side validation enabled; forms without it are exposed.
- The bundled contact form enables VALID_EMAIL and is not affected.

## Fix

- Upgrade baserCMS to `5.3.2` (5.3 line) or `5.4.2` (5.4 line).
- Until upgraded, enable VALID_EMAIL validation on any public form with an email-type field.

## Timeline

- 2026-10-23T21:57:34+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-115479
- 2026-10-25T12:38:50+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2026-115479

## From the sources

baserCMS is a website development framework. In versions 5.2.5 before 5.3.2 and 5.4.0 before 5.4.2, an unauthenticated visitor can supply a comma-separated address list in a public mail form's email field and cause a single auto-reply to be addressed to multiple third parties. MailMessageMailer::sendFormToUser() passes the visitor-controlled userMail value to parseAndNormalizeMailAddresses(), which splits it with explode(',') and supplies every resulting address to setTo(). Newly created forms with an email-type field are affected when the separate, optional VALID_EMAIL server-side validation is not enabled; browser type=email validation does not prevent crafted requests. The bundled contact form enables VALID_EMAIL and is not affected. The auto-reply uses the site's sender identity and includes partially attacker-controlled content, allowing abuse of the site to deliver unsolicited mail. This issue has been patched in versions 5.3.2 and 5.4.2.

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