CVE-2026-115480 baserproject CVE debrief

Who should care

Defenders responsible for baserCMS deployments, especially those with public-facing API endpoints, should assess exposure and prioritize patching to prevent potential spam and auto-replies.

Why it matters

CVE-2026-115480 allows unauthenticated attackers to bypass image CAPTCHA on the public Web API mail-form submission endpoint in baserCMS, potentially leading to spam, auto-replies, and database record accumulation. Defenders should prioritize verifying exposure, especially for unauthenticated API endpoints, and assess the impact of potential spam and auto-replies.

• Potential spam generation in administrator inboxes
• Possible auto-replies to third-party email systems
• Accumulation of mail_messages database records
• Verification of exposure and impact required

Technical summary

The public POST /baser/api/bc-mail/mail_messages/add/{mailContentId}.json endpoint in baserCMS versions 5.0.0 before 5.3.2 and 5.4.0 before 5.4.2 does not enforce the form's auth_captcha setting. This allows unauthenticated attackers to automate submissions without solving the image challenge, potentially leading to spam, auto-replies, and database record accumulation. The API disables FormProtection and has no rate limit. The missing CAPTCHA check is a separate control failure from the isAccepting() check added for CVE-2026-30878.

Defensive priority

Defenders should prioritize verifying exposure, especially for unauthenticated API endpoints, and assess the impact of potential spam and auto-replies.

Recommended defensive actions

• Verify if the public Web API mail-form submission endpoint is exposed and accessible
• Assess the potential impact of spam and auto-replies on administrator inboxes and third-party email systems
• Prioritize patching to versions 5.3.2 or 5.4.2
• Monitor for suspicious mail_messages database record accumulation
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented

Evidence notes

The CVE record and source item provide details on the vulnerability, affected versions, and patches. However, the corpus does not establish versions, exploitation, impact, or remediation beyond vendor-provided information.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.