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TI-2026-85057 Aliases CVE-2026-121946GHSA-5gqw-c8wj-82xp

CRLF header injection in zbateson mail-mime-parser message builders

Priority HIGH 70CWE-93Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Attack requirements
None
Impact type
—
Confidentiality · integrity · availability
Low · Low · None
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA.

Summary

zbateson mail-mime-parser from 0.3.0 before 3.0.9 and from 4.0.0 before 4.0.6 is affected. Its message-building helpers fail to strip CR and LF characters, a CRLF header injection flaw (CWE-93). A remote attacker who supplies crafted MIME type, charset, encoding, micalg or protocol values can inject extra header lines, such as a forged Bcc, into outgoing messages without authentication or user interaction.

Written with Claude Haiku 5.5 from the sources below · 2026-11-04

Description from the CNA

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00325 25th percentileScored 2026-11-07
Fix Fixed mail-mime-parser (zbateson): 3.0.9, 4.0.6

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
zbatesonmail-mime-parser0.3.0 to before 3.0.9; 4.0.0 to before 4.0.63.0.9, 4.0.6Patch availableCNA
  • mail-mime-parser Vendorzbateson Affected 0.3.0 to before 3.0.9; 4.0.0 to before 4.0.6 Fixed in 3.0.9, 4.0.6 Patch available CNA

Remediation

Upgrade mail-mime-parser to 3.0.9 for the 3.x branch or to 4.0.6 for the 4.x branch, which fix the issue.

Written with Claude Haiku 5.5 from the sources below · 2026-11-04

  • Fix · CNA mail-mime-parser (zbateson) Fixed in 3.0.9, 4.0.6

Timeline

  1. 2026-11-04 Threatist record created from CVE-2026-121946
  2. 2026-11-04 Alias added: GHSA-5gqw-c8wj-82xp
  3. 2026-11-04 CISA SSVC decision points changed
  4. 2026-11-04 Priority changed: MEDIUM → HIGH

References

Patch 4

Advisory 1

Other 1

  • TI-2026-44241 zbateson/mail-mime-parser has uncontrolled resource consumption (CPU/memory DoS) parsing untrusted MIME CVSS 3.1HIGH 7.5
  • TI-2026-44240 zbateson/mail-mime-parser has CRLF header injection via attachment filename CVSS 3.1HIGH 7.2

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences