Mailpit is an email testing tool and API for developers. Versions prior to 1.28.3 are vulnerable to Server-Side Request Forgery (SSRF) via HTML Check CSS Download. The HTML Check feature (`/api/v1/message/{ID}/html-check`) is designed to analyze HTML emails for compatibility. During this process, the `inlineRemoteCSS()` function automatically downloads CSS files from external `<link rel="stylesheet" href="...">` tags to inline them for testing. Version 1.28.3 fixes the issue.
Advisories
Source ID Title
Github GHSA Github GHSA GHSA-6jxm-fv7w-rw5j Mailpit has a Server-Side Request Forgery (SSRF) via HTML Check API
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Tue, 20 Jan 2026 20:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Tue, 20 Jan 2026 08:45:00 +0000

Type Values Removed Values Added
First Time appeared Axllent
Axllent mailpit
Vendors & Products Axllent
Axllent mailpit

Mon, 19 Jan 2026 19:15:00 +0000

Type Values Removed Values Added
Description Mailpit is an email testing tool and API for developers. Versions prior to 1.28.3 are vulnerable to Server-Side Request Forgery (SSRF) via HTML Check CSS Download. The HTML Check feature (`/api/v1/message/{ID}/html-check`) is designed to analyze HTML emails for compatibility. During this process, the `inlineRemoteCSS()` function automatically downloads CSS files from external `<link rel="stylesheet" href="...">` tags to inline them for testing. Version 1.28.3 fixes the issue.
Title Mailpit Vulnerable to Server-Side Request Forgery (SSRF) via HTML Check API
Weaknesses CWE-918
References
Metrics cvssV3_1

{'score': 5.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-01-20T20:05:35.862Z

Reserved: 2026-01-16T15:46:40.842Z

Link: CVE-2026-23845

cve-icon Vulnrichment

Updated: 2026-01-20T20:04:05.285Z

cve-icon NVD

Status : Received

Published: 2026-01-19T19:16:04.820

Modified: 2026-01-19T19:16:04.820

Link: CVE-2026-23845

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-01-20T08:40:27Z

Weaknesses