CVE-2026-61815 zbateson/mail-mime-parser has CRLF header injection via attachment filename
Attackers can inject CRLF sequences into attachment filenames to forge headers, potentially exfiltrating emails via Bcc injection in applications using this library.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-61815?
CVE-2026-61815 is a high-severity vulnerability in zbateson mail-mime-parser, published on 24 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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).
Weakness: CWE-93
Which versions are affected by CVE-2026-61815?
4 open source packages ship an affected version, including zbateson/mail-mime-parser.
| Package | Affected | Fixed in |
|---|---|---|
zbateson/mail-mime-parser Packagist | All versions | 3.0.6 |
zbateson/mail-mime-parser Packagist | All versions | 3.0.6 |
zbateson/mail-mime-parser Packagist | From 4.0.0 | 4.0.2 |
zbateson/mail-mime-parser Packagist | From 4.0.0 | 4.0.2 |
How do I fix CVE-2026-61815?
Upgrade zbateson/mail-mime-parser to a fixed version for your release line: 3.0.6 or 4.0.2.
Is CVE-2026-61815 being exploited?
There is no known exploitation of CVE-2026-61815 in the wild and no public exploit code.
Sources
Also known as GHSA-36h5-qg4p-q2qf.