---
id: CVE-2026-84697
title: >-
  Mailpit's IsInternalIP deny list function fails to block the Azure WireServer
  address 168.63.129.16 and the RFC 2765/6145 IPv4-translated IPv6 prefix,
  allowing server-side request forgery to internal destinations
summary: >-
  Mailpit's IsInternalIP deny list function fails to block the Azure WireServer
  address 168.63.129.16 and the RFC 2765/6145 IPv4-translated IPv6 prefix,
  allowing server-side request forgery to internal destinations. Attackers can
  supply ho…
severity: medium
cvss: 5.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N'
cwe:
  - CWE-918
published: '2026-09-02'
updated: '2026-09-10'
sourceUpdated: '2026-09-10T15:53:23.707'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-84697'
references:
  - url: 'https://github.com/axllent/mailpit'
    label: disclosure@vulncheck.com
  - url: 'https://github.com/axllent/mailpit/blob/v1.31.0/internal/tools/net.go'
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/axllent/mailpit/commit/a02821bf3424da9196e156c422370f4868a1dff2
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/mailpit-ssrf-deny-list-bypass-via-azure-metadata-and-ipv6-prefix
    label: disclosure@vulncheck.com
tags:
  - nvd
epss: 0.00245
epssPercentile: 0.15962
ingestedAt: '2026-09-10T16:57:28.700Z'
---

## Overview

Mailpit's IsInternalIP deny list function fails to block the Azure WireServer address 168.63.129.16 and the RFC 2765/6145 IPv4-translated IPv6 prefix, allowing server-side request forgery to internal destinations. Attackers can supply hostnames resolving to these addresses in message content to reach the link check API and proxy endpoint for accessing internal resources.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.