CVE-2026-21859 | THREATINT

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.

PUBLISHED Reserved 2026-01-05 | Published 2026-01-07 | Updated 2026-01-08 | Assigner GitHub_M

MEDIUM: 5.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N

Problem types

CWE-918: Server-Side Request Forgery (SSRF)

Product status

< 1.28.1

affected

References

github.com/...ailpit/security/advisories/GHSA-8v65-47jx-7mfr exploit

github.com/...ailpit/security/advisories/GHSA-8v65-47jx-7mfr

github.com/...ommit/3b9b470c093b3d20b7d751722c1c24f3eed2e19d

cve.org (CVE-2026-21859)

nvd.nist.gov (CVE-2026-21859)

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