CVE-2026-39791: Mailjet Email Marketing information disclosure vulnerability

medium 5.3 published 2026-10-06

Affected versions: 6.2.3 and older
Fixed in: 6.2.4 *
Latest version: 6.2.4
Severity: Medium · CVSS 5.3
Active installs: 10,000+
Type: Information disclosure

* The source does not name a fixed version; this is the first wordpress.org release after the last affected version.

What an attacker needs

Access: None. No account or login is needed (per the CVSS score).

CVSS vector (score by Patchstack): CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

What to do now

Update Mailjet Email Marketing to 6.2.4 or newer: Dashboard → Updates, or Plugins → “update now”.
If you cannot update right away, deactivate it until you can.
Turn on auto-updates for it: Plugins → “Enable auto-updates” on its row.
Not sure which version you run? Check your version against every known Mailjet Email Marketing issue. With WP-CLI: wp plugin get mailjet-for-wordpress --field=version.
If you ran an affected version and something looks off (new admin users, spam pages, redirects), run the free scan below.

The advisory

Unauthenticated Sensitive Data Exposure in Mailjet Email Marketing <= 6.2.3 versions.

Description from the CVE record, published by Patchstack (the CVE Numbering Authority), via the NVD entry for CVE-2026-39791.

References

NVD CVE-2026-39791 nvd.nist.gov
Patchstack advisory patchstack.com

Ran an affected version? Check your site for signs of a hack

The free scan reads the public side of your site and looks for spam pages, hidden redirects, injected scripts and blacklist entries. No login, no install, about a minute.

Where this data comes from

CVE record, score and references: NIST National Vulnerability Database (NVD), checked 2026-11-04. This product uses data from the NVD API but is not endorsed or certified by the NVD.
Versions and install counts: wordpress.org/plugins/mailjet-for-wordpress (Plugins API), fetched 2026-11-04.
The summary, “what an attacker needs” and “what to do” sections are our plain-English reading of the record and the plugin's release history; the quoted description is the record's own text. Spot an error? Email Daniel.