CVE-2026-23845 Details
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.
A Server-Side Request Forgery (SSRF) vulnerability has been identified in Mailpit versions prior to 1.28.3. The issue arises in the HTML Check feature of the API, which analyzes 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. The vulnerability allows attackers to send requests to internal services or cloud metadata endpoints, potentially leading to unauthorized access to sensitive information.
Users are advised to upgrade to Mailpit version 1.28.3 or later, where this vulnerability has been fixed.
Metrics
CVSS 4.0 Severity and Vector Strings:
No CVSS 4.0 data is available for this CVE.
CVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
CISA-ADP
Assessed Jan 20, 2026References to Advisories, Solutions, and Tools
By selecting these links, you will be leaving this site. These are references gathered from the official CVE record and are not endorsed by Volerion.
| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/axllent/mailpit/commit/1679a0aba592ebc8487a996d37fea8318c984dfe | [email protected] | Patch |
| https://github.com/axllent/mailpit/releases/tag/v1.28.3 | [email protected] | ProductRelease Notes |
| https://github.com/axllent/mailpit/security/advisories/GHSA-6jxm-fv7w-rw5j | [email protected] | ExploitVendor Advisory |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-918 | Server-Side Request Forgery (SSRF) | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| axllent mailpit | < 1.28.3 |
CPE
Remediation
| |
Change History
4 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jun 17, 2026 | CVE Modified | [email protected] |
| Jun 17, 2026 | CVE Modified | CISA-ADP |
| Feb 5, 2026 | Initial Analysis | [email protected] |
| Jan 19, 2026 | New CVE Received | [email protected] |