CVE-2021-44026: Roundcube Webmail SQL Injection Vulnerability

CVE-2021-44026 is an SQL injection vulnerability in Roundcube Webmail that can be triggered through the search or search_params functionality. SQL injection flaws of this class let an attacker manipulate database queries, which can expose mailbox data, credentials, or other information stored by the webmail application and may enable further compromise of the host. Because Roundcube is commonly used for organizational email access, successful abuse can affect confidentiality of communications and related account data. Confirm exact impact and affected configurations against the vendor advisory.

CISA lists the required action as applying updates per vendor instructions. Known ransomware use is not documented for this CVE.

How it works

This issue is classified as CWE-89 (SQL Injection). In Roundcube Webmail the vulnerability is reachable via search or search_params. An attacker who can submit crafted input to those parameters may cause the application to construct and execute unintended SQL statements against its backend database.

At a high level, the attacker supplies specially formed values that alter the intended query logic—for example by injecting additional clauses or operators—rather than being treated solely as data. Successful exploitation can allow unauthorized reading, modification, or deletion of database contents depending on the privileges of the database account used by the application. Exact request formats, authentication requirements, and reachable tables are not detailed in the provided facts; treat any public proof-of-concept claims with caution and verify mechanics only against the vendor advisory and your own controlled testing.

Am I affected? How to find it in your systems

Roundcube Webmail is a browser-based email client typically deployed on web servers that provide IMAP access to mailboxes for users or organizations. It often runs on Linux hosts behind a web server (Apache, nginx, etc.) and connects to a relational database such as MySQL/MariaDB or PostgreSQL.

• Inventory: Search configuration management databases, package inventories, container registries, and web-server document roots for Roundcube installations. Look for characteristic paths, configuration files (for example config.inc.php), and process or package names associated with Roundcube.
• Version and configuration check: Identify the installed Roundcube version and any custom patches or plugins. Compare the version and the presence of search-related features against the vendor advisory for CVE-2021-44026; do not rely on version numbers that are not explicitly listed in that advisory.
• Exposure surface: Note whether the webmail interface is reachable from the internet, from partner networks, or only from internal networks. Also note whether anonymous or lightly authenticated access to search functions is possible.
• Telemetry signs: Review web-server access logs and application logs for anomalous requests that target search endpoints or contain unusual characters typical of SQL injection attempts (quotes, comment sequences, UNION-style constructs, etc.). Correlate with database error logs showing syntax errors or unexpected query patterns. Absence of such logs does not prove safety; it only indicates that no obvious exploitation was recorded.

How to remediate

The primary remediation is to apply the vendor-supplied updates for Roundcube Webmail exactly as directed in the official advisory for CVE-2021-44026. CISA’s required action is to apply updates per vendor instructions; follow that guidance and verify the installation after patching.

• After updating, re-inventory the version and confirm that search and search_params handling matches the fixed behavior described by the vendor.
• For the broader SQL-injection class, ensure the application’s database account uses least privilege (no unnecessary DROP, ALTER, or administrative rights), that prepared statements or parameterized queries are used where the code is under your control, and that input validation is enforced at the application boundary.
• Rotate any database credentials that may have been exposed and review database contents for unauthorized changes if exploitation is suspected.
• Rebuild or redeploy from known-good images if the host itself may have been altered.

If you can't patch immediately

Until the vendor update can be applied, reduce the attack surface with compensating controls appropriate to an SQL-injection vulnerability in a webmail front end.

• Network segmentation: Restrict access to the Roundcube web interface to trusted networks or authenticated reverse-proxy users only; block direct internet exposure where possible.
• Virtual patching / WAF: Deploy or tune a web application firewall to inspect and block requests containing common SQL-injection patterns directed at search-related parameters. Test rules carefully to avoid breaking legitimate search functionality.
• Feature reduction: If operationally feasible, temporarily disable or tightly restrict the search feature until the patch is installed; confirm the exact configuration option with the vendor documentation.
• Monitoring and detection: Increase logging verbosity for the web server and database, alert on anomalous query patterns or repeated failed authentication followed by search activity, and retain logs long enough for forensic review.
• Credential hygiene: Enforce multi-factor authentication for webmail access and monitor for unusual mailbox activity that could indicate post-exploitation use of stolen data.

These measures lower risk but do not eliminate it; schedule the official update as soon as practicable.

If your data may have been exposed

Actively exploited vulnerabilities of this type can lead to unauthorized access to mailbox contents, address books, or other data stored by the webmail system, and may serve as a foothold for broader account compromise. If you have reason to believe exploitation occurred, treat any credentials or personal data that passed through the system as potentially exposed, force password resets, and review mail-forwarding rules and sent-item history for signs of abuse. Known ransomware use is not documented for this CVE. You can run a free exposure scan of your email address against known breach data sets to check whether associated credentials have appeared in public dumps, then prioritize remediation of any confirmed exposures.