---
id: CVE-2026-67445
title: Mailpit is an email testing tool and API for developers
summary: >-
  Mailpit is an email testing tool and API for developers. Prior to 1.30.4,
  Mailpit reads SMTP commands through internal/smtpd/smtpd.go session.readLine()
  using bufio.Reader.ReadString before session.parseLine() parses the verb or
  the RFC …
severity: medium
cvss: 5.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L'
cwe:
  - CWE-400
vendor: axllent
product: github.com/axllent/mailpit
affected:
  - github.com/axllent/mailpit <= 1.30.3
patched:
  - github.com/axllent/mailpit 1.30.4
published: '2026-08-20'
updated: '2026-09-18'
sourceUpdated: '2026-09-18T20:09:01.757'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-67445'
references:
  - url: >-
      https://github.com/axllent/mailpit/commit/993bed95b3c74d95231af93bd0e0d4c3d5b4db4d
    label: security-advisories@github.com
  - url: 'https://github.com/axllent/mailpit/releases/tag/v1.30.4'
    label: security-advisories@github.com
  - url: 'https://github.com/axllent/mailpit/security/advisories/GHSA-w878-pj84-3j5v'
    label: security-advisories@github.com
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-67445'
  - url: 'https://github.com/advisories/GHSA-w878-pj84-3j5v'
tags:
  - nvd
  - ghsa
  - go
  - score-dispute
epss: 0.00379
epssPercentile: 0.31808
aliases:
  - GHSA-w878-pj84-3j5v
ecosystem: go
scores:
  nvd: 5.3
  ghsa: 7.5
ingestedAt: '2026-09-02T23:52:22.897Z'
---

## Overview

Mailpit is an email testing tool and API for developers. Prior to 1.30.4, Mailpit reads SMTP commands through internal/smtpd/smtpd.go session.readLine() using bufio.Reader.ReadString before session.parseLine() parses the verb or the RFC 5321 512-octet command-line limit is enforced. An unauthenticated remote SMTP client can send an oversized single command line that is fully allocated before syntax rejection or timeout, and the normal MaxMessageSize and DATA limits do not apply to this pre-DATA path. The same command reader is used by handleAuthLogin(), handleAuthPlain(), and handleAuthCramMD5() continuation lines, so concurrent oversized inputs can create memory pressure and reduce service availability. This issue is fixed in version 1.30.4.

## Remediation

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

## Package advisory (CVE-2026-67445)

Affected packages:

- `github.com/axllent/mailpit <= 1.30.3`

Patched in:

- `github.com/axllent/mailpit 1.30.4`

Source: https://github.com/advisories/GHSA-w878-pj84-3j5v