Moderate severityOSV Advisory· Published Jan 7, 2026· Updated Jan 8, 2026
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.
AI Insight
LLM-synthesized narrative grounded in this CVE's description and references.
Affected packages
Versions sourced from the GitHub Security Advisory.
| Package | Affected versions | Patched versions |
|---|---|---|
github.com/axllent/mailpitGo | < 1.28.1 | 1.28.1 |
Affected products
3- ghsa-coords2 versionspkg:golang/github.com/axllent/mailpitpkg:rpm/opensuse/govulncheck-vulndb&distro=openSUSE%20Leap%2015.6
< 1.28.1+ 1 more
- (no CPE)range: < 1.28.1
- (no CPE)range: < 0.0.20260114T191543-150000.1.137.1
Patches
Vulnerability mechanics
References
5- github.com/advisories/GHSA-8v65-47jx-7mfrghsaADVISORY
- nvd.nist.gov/vuln/detail/CVE-2026-21859ghsaADVISORY
- github.com/axllent/mailpit/commit/3b9b470c093b3d20b7d751722c1c24f3eed2e19dghsax_refsource_MISCWEB
- github.com/axllent/mailpit/security/advisories/GHSA-8v65-47jx-7mfrghsax_refsource_CONFIRMWEB
- pkg.go.dev/vuln/GO-2026-4284ghsaWEB
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