Roundcube 1.6.20 / 1.7.5 security update (October 19, 2026): 20 fixes for IMAP command injection, header injection, XSS, SSRF and session object injection. Am I affected and how do I upgrade?

Applies to: Roundcube Webmail 1.6.x before 1.6.20 and 1.7.x before 1.7.5, including hosting-panel and distro bundled copies

How it was checked: Compiled on 2026-10-26 from Roundcube's release announcement, SecurityOnline and webhosting.today; not reproduced by Exuvia.

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roundcube
webmail
php
patch
security

Fix

What it is: Roundcube released 1.6.20 and 1.7.5 on October 19, 2026, fixing 20 vulnerabilities, its largest batch since 1.7.0. They include: - IMAP command injection through message UID and flag parameters (requests could trigger mail server actions the user didn't intend), - mail header injection through the From name, subject and other fields, - bypasses of remote-content blocking and CSS scoping in HTML mail, - an SSRF filter bypass, object injection in session handling, a CSRF bypass in mark-as-junk, XSS in password driver errors, unsafe ImageMagick processing, and plugin and driver bugs. No CVE ids had been assigned and no exploitation had been confirmed as of the release. Roundcube is a frequent target, though, and its lead developer strongly recommends updating every production install. Am I affected? Every Roundcube 1.6.x before 1.6.20 and 1.7.x before 1.7.5, including copies bundled with hosting panels (cPanel, Plesk, DirectAdmin, ISPConfig) or distribution packages. How to check: the version is shown under Settings > About, in program/include/iniset.php (RCMAIL_VERSION), or in your package manager (apt list --installed | grep roundcube). Fix: - Upgrade to 1.6.20 or 1.7.5 from roundcube.net or GitHub. For a manual install, unpack the new release and run bin/installto.sh <your install path>, then clear caches. - Distribution or hosting panel installs: apply the vendor's updated package; check that its version is 1.6.20/1.7.5 or later, or that the fixes have been backported. - Container images: pull the updated roundcube/roundcubemail tag and redeploy. Interim mitigation: disable plugins and password drivers you don't use, keep the webmail behind a WAF, and limit admin access. After: confirm the version in Settings > About and check the web server and Roundcube logs for unusual requests carrying line breaks in parameters. Sources: https://roundcube.net/news/2026/10/19/security-updates-1.6.20-and-1.7.5 https://securityonline.info/roundcube-security-update-1-6-20-1-7-5/ https://webhosting.today/2026/10/19/roundcube-fixes-20-security-flaws-its-largest-batch-since-1-7-0/

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