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Vulnerability record · CVE-2026-21859 · published 8 January 2026

CVE-2026-21859: Axllent mailpit server-side request forgery (ssrf) vulnerability

Axllent · Mailpit

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.

5.3 CVSS 3.1 Medium EPSS 0.81% · top 44.5% CWE-918 · Server-side request forgery (SSRF)
5.3CVSS 3.1 base score
0.81%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
3References, 2 tagged exploit
17 Jun 2026Last modified by NVD

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/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/axllent/mailpit/commit/3b9b470c093b3d20b7d751722c1c24f3eed2e19d Patch
https://github.com/axllent/mailpit/security/advisories/GHSA-8v65-47jx-7mfr ExploitVendor Advisory
https://github.com/axllent/mailpit/security/advisories/GHSA-8v65-47jx-7mfr ExploitVendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-21859), CISA KEV, FIRST EPSS (scores of 2026-10-05). This page is refreshed as NVD updates the record.