CVE-2026-15192 in sendportal
Summary
by MITRE • 07/09/2026
A vulnerability has been found in mettle sendportal up to 3.0.1. This issue affects the function sendgrid/postmark/postal/mailjet of the component APIv1 Webhooks. The manipulation leads to missing authentication. The attack is possible to be carried out remotely. The exploit has been disclosed to the public and may be used. The project was informed of the problem early through an issue report but has not responded yet.
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Analysis
by VulDB Data Team • 07/09/2026
The vulnerability in mettle sendportal version 3.0.1 represents a critical authentication bypass flaw within the APIv1 Webhooks functionality, specifically affecting the sendgrid/postmark/postal/mailjet integration components. This weakness stems from inadequate verification mechanisms that fail to properly authenticate incoming requests, creating an exploitable pathway for unauthorized access to the email delivery system. The vulnerability manifests in the webhook processing functions where legitimate authentication checks are either absent or insufficiently implemented, allowing malicious actors to bypass security controls and potentially gain control over email sending capabilities.
The technical nature of this flaw aligns with CWE-287 which addresses improper authentication vulnerabilities, and more specifically relates to CWE-305 which deals with authentication bypass through multiple attempts. The remote exploitation capability means attackers can leverage this vulnerability without requiring physical access to the system, making it particularly dangerous in cloud-based email delivery environments where such systems are often exposed to internet traffic. The vulnerability exists within the APIv1 Webhooks component, suggesting that the system relies on webhook endpoints to process incoming notifications from email service providers, and these endpoints lack proper authentication verification mechanisms.
From an operational impact perspective, this vulnerability could enable attackers to send spam emails, access sensitive email data, or manipulate email delivery workflows through unauthorized webhook requests. The exposure of the exploit to the public domain increases the likelihood of active exploitation, as cybercriminals can readily implement the discovered attack vectors against vulnerable sendportal installations. The fact that the project maintainers were informed through an issue report but have not responded indicates a potential delay in remediation that leaves systems exposed to ongoing threats. This vulnerability directly impacts the security posture of organizations using sendportal for email management, potentially leading to reputation damage, regulatory compliance issues, and financial losses due to unauthorized email activity.
Organizations should implement immediate mitigations including disabling unused webhook endpoints, implementing additional authentication layers such as API keys or HMAC signatures, and monitoring webhook traffic for suspicious patterns. The recommended approach involves applying the latest available patches from the sendportal maintainers while implementing network-level controls to restrict access to webhook endpoints. Security teams should also consider implementing webhook request validation mechanisms that verify the authenticity of incoming requests through cryptographic signatures or other authentication methods. The vulnerability highlights the importance of proper webhook security implementation and demonstrates how seemingly minor authentication gaps can lead to significant operational risks in email delivery systems, emphasizing adherence to secure coding practices as outlined in the OWASP Top Ten and NIST cybersecurity frameworks for web application security.
The public disclosure of this exploit creates an urgent need for system administrators to assess their sendportal installations and implement compensating controls. Organizations should conduct thorough vulnerability assessments to identify all instances of affected versions and ensure that proper access controls are implemented at multiple layers of their email infrastructure. The lack of response from project maintainers underscores the importance of proactive security measures and independent verification of third-party software security posture, particularly for critical components like email delivery systems that handle sensitive communications.