Threats affecting pkg:composer/mail-mime-parser

zbateson mail-mime-parser versions before 3.0.9 and 4.x before 4.0.6 have a CRLF injection vulnerability. This flaw occurs in message-building helpers that do not properly strip carriage return (CR) and line feed (LF) characters from certain header fields. 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.

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. Starting in version 2.0.0 and prior to version 3.0.6 and 4.0.2, an uncontrolled resource consumption / algorithmic complexity vulnerability (CWE-400) affects any application that parses untrusted email with this library. Three independent parsing paths are super-linear in cost, so a byte-size cap on the caller side does **not** bound the work done. A crafted message under 2 MB can consume seconds of CPU or hundreds of megabytes to multiple gigabytes of memory (leading to an out-of-memory kill), enabling denial of service. The parse is lazy, but the cost is paid on the first `getAllParts()` or content read. This is fxed in 4.0.2 and 3.0.6. The fixes add configurable limits on multipart nesting depth and on header count / total header size (recording a parse error past the threshold rather than throwing), and change sibling append to O(n). Users should upgrade to one of these (or later) versions. Versions 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. (Versions prior to 2.0 used a different parser and are not affected by all three paths.) These costs are super-linear, so an input byte-size cap alone does not bound them. Until upgrading, restrict exposure of the parser to untrusted input, and run parsing under a constrained memory_limit and execution time limit so a malicious message fails its own request rather than exhausting the host.

CVE-2026-61815 is a CRLF injection vulnerability in the zbateson mail-mime-parser library affecting versions prior to 3.0.6 and between 4.0.0 and before 4.0.2. The flaw allows attacker-controlled attachment filenames containing carriage-return and line-feed characters to inject additional MIME headers, potentially enabling header injection attacks such as forged Bcc headers. This impacts applications that parse and re-send MIME messages using this library without sanitizing attachment filenames. Versions 3.0.6 and 4.0.2 include patches for this issue. Users of older 1.x and 2.x versions are advised to upgrade or sanitize filenames to mitigate risk.