VulnerabilityAnalyzed

CVE-2026-23845

Versions prior to 1.28.3 are vulnerable to Server-Side Request Forgery (SSRF) via HTML Check CSS Download.

HIGH 7.5EPSS 0.41%

Does this matter?

High impact if exploited, but EPSS currently rates exploitation as unlikely (0.41%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.

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.

CVSS 3.1: 7.5 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
EPSS: 0.41% probability · 34th percentile
CISA KEV: Not listed
Weakness: CWE-918
Affected: axllent/mailpit
Source: security-advisories@github.com

References

https://github.com/axllent/mailpit/commit/1679a0aba592ebc8487a996d37fea8318c984dfePatch
https://github.com/axllent/mailpit/releases/tag/v1.28.3Product, Release Notes
https://github.com/axllent/mailpit/security/advisories/GHSA-6jxm-fv7w-rw5jExploit, Vendor Advisory

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.