CVE-2026-84697: Server-Side Request Forgery (SSRF) in axllent mailpit
Description
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.
CVSS v4.0
Score 6.9medium
Affected software
axllent
mailpit
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AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
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, which enables server-side request forgery (SSRF) to internal destinations. Attackers can craft message content with hostnames resolving to these addresses to exploit the link check API and proxy endpoint, potentially accessing internal resources. This vulnerability affects Mailpit versions <=1.31.0. The product is a cloud service, and the vendor manages remediation. The CVSS 4.0 score is 6.9 (medium severity). No known exploits in the wild have been reported.
Potential Impact
Successful exploitation allows an attacker to perform SSRF attacks by bypassing internal IP deny lists, potentially accessing internal resources that should be protected. This could lead to unauthorized internal network access via the link check API and proxy endpoint. However, there is no indication of privilege escalation, user interaction, or other attack vectors. The impact is limited to the ability to reach internal destinations through SSRF.
Mitigation Recommendations
A patch is available for this vulnerability. Since Mailpit is offered as a cloud service, the vendor manages remediation for the hosted environment. Users of self-hosted Mailpit should upgrade to a fixed version beyond 1.31.0 once available. Check the vendor advisory for the latest patch and remediation guidance.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- VulnCheck
- Date Reserved
- 2026-09-01T23:24:24.109Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Is Cloud Service
- true
Threat ID: 6a977a61acd9273b49923c31
Added to database: 09/02/2026, 01:22:41 UTC
Last enriched: 09/07/2026, 13:54:22 UTC
Last updated: 10/15/2026, 18:48:24 UTC
Views: 79
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