What is the CVSS score of CVE-2026-21859?

CVE-2026-21859 has a CVSS 3.1 base score of 5.8 (Medium). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N. EPSS exploitation probability: 1.0%.

Which versions of Mailpit are affected by CVE-2026-21859?

Organizations using Mailpit should be aware of moderate risk from CVE-2026-21859, a server-side request forgery vulnerability rated CVSS 5.8.. A patch is available.

Is there a public PoC exploit available for CVE-2026-21859?

Yes, a public proof-of-concept exploit is available for CVE-2026-21859. Prioritise patching immediately. EPSS: 1.0%.

How to fix or mitigate CVE-2026-21859?

Within 30 days: Identify affected systems and apply vendor patches as part of regular patch cycle. Vendor patch is available.

Mailpit CVE-2026-21859

MEDIUM

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

2026-01-08 security-advisories@github.com

GHSA-8v65-47jx-7mfr

SSRF Mailpit Suse

5.8

CVSS 3.1 · GitHub Advisory

Severity by source

GitHub Advisory PRIMARY

5.8 MEDIUM

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

SUSE

MEDIUM

qualitative

Primary rating from GitHub Advisory.

CVSS VectorGitHub Advisory

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

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Changed

Confidentiality

Low

Integrity

None

Availability

None

Lifecycle Timeline

Analysis Generated

Mar 12, 2026 - 21:54 vuln.today

PoC Detected

Feb 02, 2026 - 19:16 vuln.today

Public exploit code

Patch released

Feb 02, 2026 - 19:16 nvd

Patch available

CVE Published

Jan 08, 2026 - 00:16 nvd

MEDIUM 5.8

DescriptionGitHub Advisory

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.

AnalysisAI

Mailpit versions 1.28.0 and earlier contain a server-side request forgery vulnerability in the /proxy endpoint that permits unauthenticated attackers to probe and access internal network resources and services. The endpoint insufficiently validates destination addresses, allowing requests to internal IP ranges despite scheme validation. Public exploit code exists for this vulnerability, which is resolved in version 1.28.1.

Technical ContextAI

Classified as CWE-918 (Server-Side Request Forgery (SSRF)). Affects 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.