Historical catalog analysis: CISA added this entry on June 09, 2025. The entry reflects catalog information retrieved on August 31, 2026, not a snapshot archived on the inclusion date. Check current vendor guidance before acting.
What the vulnerability is
CVE-2024-42009 is a Cross-Site Scripting (XSS) vulnerability identified in Roundcube Webmail. The flaw stems from a desanitization issue within the message_body() function located in program/actions/mail/show.php. This technical failure could allow a remote attacker to steal and send emails of a victim via a crafted email message.
Exposure and applicability
This vulnerability affects organizations deploying Roundcube Webmail. The exposure path is external; the trigger is a crafted email received by the target user. If successful, the exploit could enable the attacker to perform unauthorized actions, such as stealing or sending emails on behalf of the victim.
Remediation priorities
Based on our analysis, vulnerability management teams should prioritize the following actions:
- Identify Affected Assets: Locate all instances of Roundcube Webmail across the infrastructure. Because this is a web-facing mail interface, these assets are high-priority targets for exposure reduction.
- Apply Vendor Updates: Deploy the security updates provided by the vendor to address the desanitization flaw in
show.php. - Review Cloud Service Configurations: For organizations utilizing Roundcube via cloud providers, verify that the provider has applied the necessary mitigations.
- Decommission Unpatched Instances: If mitigations cannot be applied or are unavailable for a specific version, the product should be discontinued to eliminate the exposure.
How to validate remediation
To ensure that the risk has been reduced, defenders should move beyond simple version checks. While confirming the installed version matches the patched release is a necessary first step, it does not prove the fix was applied correctly across all active nodes in a load-balanced environment.
Validation should include:
* Configuration Audit: Verifying that the program/actions/mail/show.php file reflects the updated logic provided by the vendor.
* Deployment Verification: Confirming that the update is consistent across all web servers serving the Roundcube interface to prevent “version drift” where some nodes remain vulnerable.
Limits and open questions
Applying a patch reduces the likelihood of this specific XSS vector being successful, but it does not eliminate the residual risk of other undiscovered vulnerabilities within the mail rendering engine. It remains unknown whether this vulnerability has been utilized in known ransomware campaigns. Furthermore, while patching addresses the root cause, it does not recover any data or session tokens that may have been compromised prior to the update.
Source and editorial note
CVE-2024-42009: RoundCube Webmail Cross-Site Scripting Vulnerability · Source date: June 09, 2025 · Retrieved August 31, 2026.
Material facts are tied to the cited primary source. Recommendations are independent defensive analysis unless attributed to the source. Confirm consequential decisions against current authoritative guidance.
Archive date: June 12, 2025. The displayed post date is assigned three days after the source date to organize this retrospective archive; it does not mean this site published the analysis then. First published by this site: October 12, 2026 at 00:27 UTC.
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