CVE-2026-23845

MEDIUM

Mailpit < 1.28.3 - Server-Side Request Forgery via HTML Check CSS Download

Title source: llm

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.

References (3)

Core 3

Core References

Exploit, Vendor Advisory x_refsource_confirm

https://github.com/axllent/mailpit/security/advisories/GHSA-6jxm-fv7w-rw5j

Patch x_refsource_misc

https://github.com/axllent/mailpit/commit/1679a0aba592ebc8487a996d37fea8318c984dfe

Product, Release Notes x_refsource_misc

https://github.com/axllent/mailpit/releases/tag/v1.28.3

Scores

CVSS v3 5.8

EPSS 0.0040

EPSS Percentile 31.2%

Attack Vector NETWORK

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N

CISA SSVC

Vulnrichment

Exploitation none

Automatable yes

Technical Impact partial

Details

CWE

CWE-918

Status published

Products (2)

axllent/mailpit < 1.28.3

axllent/mailpit 0 - 1.28.3Go

Published Jan 19, 2026

Tracked Since Feb 18, 2026