IRONSMITHINTEL
MEDIUMCVSS6.1
|
Actively Exploited
|CISA KEV|CVE-2020-13965|Auth: none — unauthenticated|Reboot: required|Manual only

Roundcube Webmail Cross-Site Scripting (XSS) Vulnerability

Roundcube Webmail contains a cross-site scripting (XSS) vulnerability that allows a remote attacker to manipulate data via a malicious XML attachment.

Published Jun 9, 2020 · Updated May 16, 2026
Why patchRisk explained in plain English
Worst-case scenarioIf unpatched

A remote attacker, without authentication, can achieve partial data exposure, partial data tampering. Federal agencies are required to remediate by 2024-07-17 under CISA BOD 22-01.

How the attack worksNo clicks needed

This is a Cross-Site Scripting (XSS) (CWE-79) vulnerability in Roundcube Webmail. An issue was discovered in Roundcube Webmail before 1.3.12 and 1.4.x before 1.4.5. There is XSS via a malicious XML attachment because text/xml is among the allowed types for a preview. Exploitation requires remote network access, low attack complexity, no authentication required, and user interaction required.

📧

Phishing link

🖼

Malicious file

🔓

Server compromised

Am I affected?Quick check

Probably yes if any of these apply:

IT Security
Running webmail: v < 1.3.12, 1.4.0 ≤ v < 1.4.5; debian linux: 9.0, 10.0; fedora: 31, 32
Real-world incidentsWhat we've seen

Active exploitation documented in the wild. Threat-research write-up: https://github.com/DrunkenShells/Disclosures/tree/master/CVE-2020-13965-Cross%20Site-Scripting%20via%20Malicious%20XML%20Attachment-Roundcube

How to patch

Manual remediation steps

Apply the Vendor Patch

This vulnerability is in the CISA Known Exploited Vulnerabilities catalog — apply the vendor's security update as soon as possible.

CISA required action: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

References

    1
    Vendor advisory: https://roundcube.net/news/2020/06/02/security-updates-1.4.5-and-1.3.12
    1
    NVD entry: https://nvd.nist.gov/vuln/detail/CVE-2020-13965
    1
    CISA KEV: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2020-13965
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