Vulnerability Description
Mailpit is an email testing tool and API for developers. Prior to version 1.30.0, the Mailpit SMTP server has a Server.MaxSize int field that controls the maximum allowed DATA payload size, but the field is never assigned anywhere outside test code, leaving it at Go's zero value (0 ⇒ "no limit"). The same applies to the HTTP /api/v1/send endpoint, whose request body is decoded with json.NewDecoder(r.Body) and no http.MaxBytesReader. Because Mailpit's default listeners bind [::]:1025 (SMTP) and [::]:8025 (HTTP), with no authentication required on either, a single network-reachable attacker can push an arbitrarily large message into Mailpit and watch RAM consumption spike with a ~7-10× amplification factor (raw frame → enmime envelope tree → search-text index → zstd-encoded write to SQLite). Repeating the attack — or running it concurrently from multiple connections — drives the process to OOM-kill. Version 1.30.0 contains a patch.
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Axllent | Mailpit | < 1.30.0 |
Related Weaknesses (CWE)
References
- https://github.com/axllent/mailpit/releases/tag/v1.30.0Release Notes
- https://github.com/axllent/mailpit/security/advisories/GHSA-fpxj-m5q8-fphwExploitVendor Advisory
- https://github.com/axllent/mailpit/security/advisories/GHSA-fpxj-m5q8-fphwExploitVendor Advisory
FAQ
What is CVE-2026-45713?
CVE-2026-45713 is a vulnerability with a CVSS score of 7.5 (HIGH). Mailpit is an email testing tool and API for developers. Prior to version 1.30.0, the Mailpit SMTP server has a Server.MaxSize int field that controls the maximum allowed DATA payload size, but the fi...
How severe is CVE-2026-45713?
CVE-2026-45713 has been rated HIGH with a CVSS base score of 7.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-45713?
Check the references section above for vendor advisories and patch information. Affected products include: Axllent Mailpit.