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CVE-2026-121946VulnerabilityPublished

zbateson mail-mime-parser before 3.0.9 and 4.x before 4.0.6 contains a CRLF header injection vulnerability in

Source GCVE Database

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Authoritative record:CVE-2026-121946· Medium 6.9

Not known to be exploited · CVSS 6.9 Medium : upgrade to 4.0.6 or 3.0.9 when convenient.

Data as of 4 Nov 2026, 16:43 UTC

CVSS 4.0 base score
6.9Medium
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (VulnCheck)CVSS 4.06.9
CNA (VulnCheck)CVSS 3.17.2
Patch
Available – fixed in 4.0.6, 3.0.9
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 4 Nov 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 4 Nov 2026.

What to do

Upgrade mail-mime-parser to 4.0.6 or 3.0.9.

Affected software

ProductAffectedFixed in
zbatesonmail-mime-parserAffected
  • >=4.0.0 <4.0.6
Fixed in
  • 4.0.6
zbatesonmail-mime-parserAffected
  • >=0.3.0 <3.0.9
Fixed in
  • 3.0.9
Packagistmail-mime-parserpkg:composer/mail-mime-parserOther threatsAffected
  • >=0.3.0 <3.0.9
  • >=4.0.0 <4.0.6
Fixed in
  • 3.0.9
  • 4.0.6

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

If you cannot patch yet, avoid using affected versions or sanitize inputs to message-building helpers to remove CR and LF characters. Monitor vendor channels for official patches or updates addressing this vulnerability.

Description

zbateson mail-mime-parser versions before 3.0.9 and 4.x before 4.0.6 have a CRLF header injection vulnerability. This flaw occurs in message-building helpers that do not properly strip carriage return (CR) and line feed (LF) characters. An attacker can exploit this by supplying crafted MIME type, charset, encoding, micalg, or protocol values to inject additional header lines, such as a forged Bcc, into outgoing email messages.

References

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