CVE-2026-21859CWE-918

Mailpit Proxy Endpoint is Vulnerable to Server-Side Request Forgery (SSRF)

Medium · published January 7, 2026

CVSS v3.1
5.8
EPSS
1%
Percentile
56.6
In the wild
Unconfirmed
What it is

Mailpit is an email testing tool and API for developers. Versions 1.28.0 and below have a Server-Side Request Forgery (SSRF) vulnerability in the /proxy endpoint, allowing attackers to make requests to internal network resources. The /proxy endpoint validates http:// and https:// schemes, but it does not block internal IP addresses, enabling attackers to access internal services and APIs. This vulnerability is limited to HTTP GET requests with minimal headers. The issue is fixed in version 1.28.1.

The record
Technical detail
CVSS v3.1
5.8 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N
CVSS v4.0
Not supplied
EPSS
0.00813 · 56.6th percentile
Weakness
CWE-918 · Server-Side Request Forgery (SSRF)
Published
2026-01-07T23:24Z
EPSS history
Timeline
  • 07 JAN 23:24Z
    Mailpit Proxy Endpoint is Vulnerable to Server-Side Request Forgery (SSRF)
    cvelistv5