baserCMS: Public Web API mail-form submission bypasses image CAPTCHA

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

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.

Source published

23 Oct 2026 13:37:32 UTC

Source modified

23 Oct 2026 13:37:32 UTC

Observed here

23 Oct 2026 16:01:20 UTC

Source terms

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CVSS 3.1 · 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N