CVE-2026-23845

EUVD-2026-3296
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.
SSRF
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
NISTPrimary
5.8 MEDIUM
NETWORK
LOW
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N
GitHub_MCNA
5.8 MEDIUM
NETWORK
LOW
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N
Base Score
CVSS 3.x
EPSS Score
Percentile: 17%
Affected Products (NVD)
VendorProductVersion
axllentmailpit
𝑥
< 1.28.3
𝑥
= Vulnerable software versions
Common Weakness Enumeration
References
https://github.com/axllent/mailpit/commit/1679a0aba592ebc8487a996d37fea8318c984dfe
https://github.com/axllent/mailpit/releases/tag/v1.28.3
https://github.com/axllent/mailpit/security/advisories/GHSA-6jxm-fv7w-rw5j