Mime Mail security updates, in plain English

Mime Mail

51,019 sites report using it · on drupal.org · 1 security update explained here

This module allows a website to send emails containing formatted text and images.

Below is every security update for Mime Mail that this site has covered, newest first. Each one says who could exploit it, whether it applies to your site, how urgent it is, and what to tell your developer. If your site uses this module and you are not sure which version, that is the first question to ask whoever looks after it.

Mime Mail

Moderately critical · 51,019 sites report using it · SA-CONTRIB-2026-312 · on drupal.org · Week of 4 November 2026

The module might include private uploaded files in outgoing emails. Anyone could potentially see this hidden information if they know the file names in advance. They would not be able to alter any information on the site.

Who could do thisAnyone visiting the site. No login needed.
Does it apply to youSites are affected under rare configurations where an attacker can send formatted emails and set the recipient list.
Has it been used in attacksNo sign of it.
How urgentDrupal rates this moderately critical. Include it in your next routine update, within the month.

Tell your developerUpdate Mime Mail to 2.0.4.

For developers: what the fix changed

The fix modifies the path validation in MimeMailFormatHelper.php by appending a directory separator to the public path and using str_starts_with to ensure the file is strictly within the public directory.

2.0.3 to 2.0.4 1 commit, 1 file.

src/Utility/MimeMailFormatHelper.php +2 −1 fix

Full diff, 2.0.3 to 2.0.4

The comparison is against the release immediately before the fix. If your site is on an older release, more will have changed.

Get in touch

Tell me who you are, what your organisation does, and what you need. That might be a Drupal site that needs looking after, an upgrade to get done before December, or an agency that needs Drupal cover.

If I can help, I'll say so and suggest a call. If I can't, I'll tell you straight away rather than waste your time.

For context: I work mainly with UK membership bodies, charities and research organisations, and with the agencies that look after their websites. Not recruiters.

Or start smaller and connect with me on LinkedIn. That's where I post what I find digging around in charity and grants data, and where the free tools turn up first.

Mime Mail

Mime Mail

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