CVE-2026-45713: 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 payl

highCVSS 7.5CVE-2026-45713

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.

Details

Source: NVD Recent CVEs (US · database · site)
Severity: high — CVSS 7.5
Published: 2026-07-20
Last updated: 2026-07-21
Exploitation: Not in CISA KEV at last sync

Original advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-45713

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Low exploitation riskCVE-2026-457130.39% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 32% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-45713	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

medium[UPDATE] [medium] MailPit: Multiple vulnerabilitiescert-bund

Recent advisories for Mailpit is an

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

medium[NEW] [medium] MailPit: Vulnerability allows disclosure of informationcert-bund · 2026-07-29
medium[UPDATE] [medium] MailPit: Vulnerability allows Denial of Servicecert-bund · 2026-07-21
medium[UPDATE] [medium] MailPit: Multiple vulnerabilitiescert-bund · 2026-07-21
mediumCVE-2026-48824: Mailpit is an email testing tool and API for developers. Prior to version 1.30.1, the fix for …nvd · 2026-07-20
mediumCVE-2026-45712: Mailpit is an email testing tool and API for developers. Prior to version 1.30.0, the screensh…nvd · 2026-07-20
mediumCVE-2026-45711: Mailpit is an email testing tool and API for developers. Prior to version 1.30.0, the mailpit …nvd · 2026-07-20