CVE-2026-55187 Details
Description
Mailpit is an email testing tool and API for developers. Prior to 1.30.2, the remediation shipped for CVE-2026-27808 is incomplete because the tools.IsInternalIP deny-list in internal/tools/net.go relies on Go's standard library classification helpers and does not block IPv6 transition mechanisms or prefixes such as NAT64, 6to4, IPv4-compatible IPv6, ISATAP, fec0::/10, and 2001:db8::/32. An attacker who can deliver email and invoke POST /api/v1/message/{ID}/link-check can coerce the Link Check API's safeDialContext path into dialing internal destinations and can use status-code and error feedback to map internal service reachability, including cloud metadata endpoints. This issue is fixed in version 1.30.2.
A vulnerability in Mailpit, an email testing tool for developers, allows for server-side request forgery (SSRF) by exploiting unblocked IPv6 transition mechanisms. This issue is present in versions prior to 1.30.2. The vulnerability arises because the 'IsInternalIP' function does not properly deny-list certain IPv6 forms that can be used to access internal resources or cloud metadata endpoints. An attacker who can send emails and use the Link Check API can manipulate the system into dialing internal destinations, potentially leading to unauthorized service discovery or access to sensitive metadata.
Users are advised to upgrade to Mailpit version 1.30.2 or later, where this vulnerability has been addressed.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed Jul 10, 2026CISA-ADP
Assessed Jul 13, 2026References to Advisories, Solutions, and Tools
By selecting these links, you will be leaving this site. These are references gathered from the official CVE record and are not endorsed by Volerion.
| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/axllent/mailpit/security/advisories/GHSA-w4mc-hhc6-xp28 | CISA-ADP | AdvisoryExploitRemedyVendor |
| https://github.com/axllent/mailpit/commit/a88dadbbe1df016a35a445089ef2a362a6c2de78 | [email protected] | Source CodeVendor |
| https://github.com/axllent/mailpit/releases/tag/v1.30.2 | [email protected] | Release NotesVendor |
| https://github.com/axllent/mailpit/security/advisories/GHSA-w4mc-hhc6-xp28 | [email protected] | AdvisoryExploitRemedyVendor |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-918 | Server-Side Request Forgery (SSRF) | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| Axllent Mailpit | <= 1.30.1 (semver) |
CPE
Remediation
| |
Change History
2 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jul 13, 2026 | CVE Modified | CISA-ADP |
| Jul 10, 2026 | New CVE Received | [email protected] |