zbateson/mail-mime-parser has CRLF header injection via attachment filename

published 2026-09-24 45 d ago modified 2026-10-05 34 d ago also GHSA-36h5-qg4p-q2qf , EUVD-2026-86335

cvss: 7.2; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.2%; EPSS 0.2% chance of exploitation in 30 days, percentile 7%
public exploits: 0; none known

zbateson/mail-mime-parser is a mail mime parser alternative to PHP's imap* functions and Pear libraries for reading messages in Internet Message Format RFC 822. Prior to version 3.0.6 and 4.0.2, CRLF (carriage-return / line-feed) header injection (CWE-93) affecting any application that uses this library to build or forward MIME messages with an attacker-influenced attachment filename. Attachment filenames are interpolated into the `Content-Type` and `Content-Disposition` header values without stripping CR/LF, so a filename containing `\r\n` serializes as one or more additional, attacker-controlled header lines (for example a forged `Bcc:` that silently exfiltrates a copy of the outgoing message). The untrusted filename can come directly from parsed inbound mail, so no local construction is required — an application that re-attaches or re-sends a parsed filename is exposed. Versions 3.0.6 and 4.0.2 patch the issue. Versions 1.x and 2.x are also affected but are end-of-life and will not receive patches; users on those lines should upgrade to a fixed release. If upgrading is not immediately possible, strip CR and LF from any filename before passing it to attachment APIs, and from the result of getFilename() before reusing it in a constructed message — e.g. preg_replace('/[\r\n]+/', ' ', $filename).

Patch / fix

fixed in 1 links 4

packagist zbateson/mail-mime-parser 3.0.6, 4.0.2

CISA SSVC

Exploitation: none
Automatable: yes
Technical impact: partial
Assessed: 34 d ago (2026-10-05)

Exploit prediction

0.18% chance of exploitation in the next 30 days, higher than 7% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	7.2	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N
GitHub	3.1	7.2	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N

Affected packages

ecosystem	package	affected	fixed in
packagist	zbateson/mail-mime-parser	<3.0.6 >=4.0.0, <4.0.2	3.0.6 4.0.2

Affected products

zbateson mail-mime-parser

Classification

Weakness

CWE-93 Improper Neutralization of CRLF Sequences

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary