CVE-2026-21859 PoC — Mailpit Proxy Endpoint is Vulnerable to Server-Side Request Forgery (SSRF)

Source

https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2026/CVE-2026-21859.yaml

Associated Vulnerability

Title:Mailpit Proxy Endpoint is Vulnerable to Server-Side Request Forgery (SSRF) (CVE-2026-21859)
Description: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.

Description

Mailpit <= 1.28.0 contains a server-side request forgery caused by insufficient validation of internal IP addresses in the /proxy endpoint, letting attackers make requests to internal network resources, exploit requires crafted HTTP GET requests.

File Snapshot


 id: CVE-2026-21859

info:
  name: Mailpit < 1.28.3 - Server-Side Request Forgery
  author: omarkurt


...

Shenlong Bot has cached this for you

Remarks

1. It is advised to access via the original source first.

2. Local POC snapshots are reserved for subscribers — if the original source is unavailable, the local mirror is part of the paid plan.

View subscription plans →

Goal Reached Thanks to every supporter — we hit 100%!