VulnerabilityAnalyzed

CVE-2026-21859

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.

MEDIUM 5.3EPSS 0.83%

Does this matter?

Lower severity and a low EPSS score (0.83%). Track it; it rarely justifies an emergency change on its own.

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.

CVSS 3.1: 5.3 MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
EPSS: 0.83% probability · 55th percentile
CISA KEV: Not listed
Weakness: CWE-918
Affected: axllent/mailpit
Source: security-advisories@github.com

References

https://github.com/axllent/mailpit/commit/3b9b470c093b3d20b7d751722c1c24f3eed2e19dPatch
https://github.com/axllent/mailpit/security/advisories/GHSA-8v65-47jx-7mfrExploit, Vendor Advisory
https://github.com/axllent/mailpit/security/advisories/GHSA-8v65-47jx-7mfrExploit, Vendor Advisory

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.