baserproject BaserCMS up to 5.3.1/5.4.1 Mail Messages API BcCaptchaService::check improper authentication

Summaryinfo

A vulnerability classified as critical was found in baserproject BaserCMS up to 5.3.1/5.4.1. This affects the function BcCaptchaService::check of the component Mail Messages API. Executing a manipulation can lead to improper authentication. This vulnerability is registered as CVE-2026-115480. It is possible to launch the attack remotely. No exploit is available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in baserproject BaserCMS up to 5.3.1/5.4.1. It has been declared as critical. This vulnerability affects the function BcCaptchaService::check of the component Mail Messages API. The manipulation with an unknown input leads to a improper authentication vulnerability. The CWE definition for the vulnerability is CWE-287. When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct. As an impact it is known to affect integrity, and availability. CVE summarizes:

baserCMS is a website development framework. In versions 5.0.0 before 5.3.2 and 5.4.0 before 5.4.2, the public POST /baser/api/bc-mail/mail_messages/add/{mailContentId}.json endpoint accepts submissions without enforcing the form's auth_captcha setting. BcMail\Controller\Api\MailMessagesController::add() and MailMessagesService::create() omit the BcCaptchaService::check() verification of captcha_id and auth_captcha performed by MailController::submit() in the web UI. An unauthenticated attacker who can reach the API can therefore automate submissions without solving the enabled image challenge. The API disables FormProtection and has no rate limit; submissions can generate administrator-inbox spam, send attacker-influenced auto-replies to third parties when an email field is present, and accumulate mail_messages database records when save_info is enabled. The API already enforces the isAccepting() check added for CVE-2026-30878; the missing CAPTCHA check is a separate control failure. This issue has been patched in versions 5.3.2 and 5.4.2.

The advisory is available at github.com. This vulnerability was named CVE-2026-115480 since 10/22/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. Technical details are known, but there is no available exploit.

Upgrading to version 5.3.2 or 5.4.2 eliminates this vulnerability.

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Productinfo

Type

• Content Management System

Vendor

• baserproject

Name

• BaserCMS

Version

• 5.3.0
• 5.3.1
• 5.4.0
• 5.4.1

License

• open-source

Website

• Product: https://github.com/baserproject/basercms/

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