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Vulnerability record · CVE-2026-23845 · published 19 January 2026

CVE-2026-23845: Axllent mailpit server-side request forgery (ssrf) vulnerability

Axllent · Mailpit

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.

7.5 CVSS 3.1 High EPSS 0.44% · top 64.4% CWE-918 · Server-side request forgery (SSRF)
7.5CVSS 3.1 base score
0.44%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
3References, 1 tagged exploit
17 Jun 2026Last modified by NVD

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/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/axllent/mailpit/commit/1679a0aba592ebc8487a996d37fea8318c984dfe Patch
https://github.com/axllent/mailpit/releases/tag/v1.28.3 ProductRelease Notes
https://github.com/axllent/mailpit/security/advisories/GHSA-6jxm-fv7w-rw5j ExploitVendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-23845), CISA KEV, FIRST EPSS (scores of 2026-09-29). This page is refreshed as NVD updates the record.