CVE-2026-115479: baserCMS: Mail-form auto-replies accept multiple visitor-controlled recipients

Severity: medium (CVSS 5.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-10-23 · updated 2026-10-30
Weakness: CWE-20

Description

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.

Affected products

baserproject basercms: from 5.2.5, < 5.3.2; from 5.4.0, < 5.4.2

References

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