---
id: CVE-2026-121946
title: >-
  zbateson mail-mime-parser before 3.0.9 and 4.x before 4.0.6 CRLF Header
  Injection via Message Builders
summary: >-
  zbateson mail-mime-parser before 3.0.9 and 4.x before 4.0.6 contains a CRLF
  header injection vulnerability in message-building helpers that fail to strip
  CR and LF characters. Attackers supplying crafted MIME type, charset,
  encoding, mic…
severity: high
cvss: 7.2
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N'
cvssSource: cna
cwe:
  - CWE-93
vendor: zbateson
product: mail-mime-parser
affected:
  - mail-mime-parser >= 0.3.0 < 3.0.9
  - mail-mime-parser >= 4.0.0 < 4.0.6
ssvc:
  exploitation: poc
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-11-04T18:48:57.168802Z'
exploitAvailable: true
published: '2026-11-04'
updated: '2026-11-04'
sourceUpdated: '2026-11-04T18:49:31.556Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-121946'
references:
  - url: >-
      https://github.com/zbateson/mail-mime-parser/security/advisories/GHSA-gmgm-r6fh-fq6g
    label: GitHub Security Advisory (GHSA-gmgm-r6fh-fq6g)
  - url: >-
      https://github.com/zbateson/mail-mime-parser/commit/f385b2923023a9a7b69003468e363a4661f1c85a
  - url: >-
      https://github.com/zbateson/mail-mime-parser/commit/1fa840ef367958e991e6840b4e3ffd41aca9d147
  - url: >-
      https://github.com/zbateson/mail-mime-parser/commit/c31c62ccc3e66a7a7da0d79954ef83807f9daa20
  - url: >-
      https://github.com/zbateson/mail-mime-parser/commit/b032920875c6cb35bb2ddd7abfd7e98608d75bc0
  - url: >-
      https://github.com/zbateson/mail-mime-parser/blob/4.0.5/src/Message/Helper/MultipartHelper.php#L270-L273
  - url: >-
      https://www.vulncheck.com/advisories/zbateson-mail-mime-parser-before-3.0.9-and-4-x-before-4.0.6-crlf-header-injection-via-message-builders
    label: >-
      VulnCheck Advisory: zbateson mail-mime-parser before 3.0.9 and 4.x before
      4.0.6 CRLF Header Injection via Message Builders
tags:
  - cve.org
  - exploit-available
ingestedAt: '2026-11-05T21:36:00.499Z'
epss: 0.00325
epssPercentile: 0.2572
---

## Overview

zbateson mail-mime-parser before 3.0.9 and 4.x before 4.0.6 contains a CRLF header injection vulnerability in message-building helpers that fail to strip CR and LF characters. Attackers supplying crafted MIME type, charset, encoding, micalg, or protocol values can inject extra header lines such as a forged Bcc into outgoing messages.

## Affected

- `mail-mime-parser >= 0.3.0 < 3.0.9`
- `mail-mime-parser >= 4.0.0 < 4.0.6`

## Remediation

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