CVE-2026-21859
5.8 · MEDIUMOverview
CVE-2026-21859 is a medium-severity vulnerability affecting axllent mailpit. It was published on January 8, 2026 and has a CVSS 3.1 base score of 5.8 (MEDIUM).
This vulnerability has a CVSS 3.1 base score of 5.8, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
Technical Description
Mailpit is an email testing tool and API for developers. Versions 1.28.0 and below have a Server-Side Request Forgery (SSRF) vulnerability in the /proxy endpoint, allowing attackers to make requests to internal network resources. The /proxy endpoint validates http:// and https:// schemes, but it does not block internal IP addresses, enabling attackers to access internal services and APIs. This vulnerability is limited to HTTP GET requests with minimal headers. The issue is fixed in version 1.28.1.
Remediation
Check the references section for vendor advisories and patches from axllent. Update mailpit to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| axllent | mailpit | >= 0, < 1.28.1 | Affected |
Frequently Asked Questions
What is CVE-2026-21859?
CVE-2026-21859 is a medium-severity vulnerability affecting axllent mailpit. It was published on January 8, 2026 and has a CVSS 3.1 base score of 5.8 (MEDIUM).
How severe is CVE-2026-21859?
This vulnerability has a CVSS 3.1 base score of 5.8, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
How do I fix or remediate CVE-2026-21859?
Check the references section for vendor advisories and patches from axllent. Update mailpit to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2026-21859?
CyberStrike's AI-powered security agents can automatically detect CVE-2026-21859 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
How CyberStrike Helps
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