# CVE-2020-35730: Roundcube Webmail Cross-Site Scripting (XSS) Vulnerability

Source: https://junglewise.ai/threats/cve-2020-35730-roundcube-webmail-cross-site-scripting-xss-vulnerability  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2023-06-22. Updated: 2026-05-10  
License: CC BY 4.0 with a link back

CVE-2020-35730 · Severity: critical · CVSS 6.1 · Exploited in the wild · Published 2023-06-22

Roundcube Webmail contains a cross-site scripting (XSS) vulnerability where JavaScript in a link reference element within a plain text email is mishandled by the linkref_addindex function in rcube_string_replacer.php. This allows a remote attacker to execute arbitrary script in the context of the victim's browser session.

Technologies: [Roundcube Webmail](https://junglewise.ai/threats/technologies/webmail). Vendors: [Roundcube](https://junglewise.ai/threats/vendors/roundcube).

## Quick answers

**Is CVE-2020-35730 exploited in the wild?** Yes. CVE-2020-35730 is known to be exploited in the wild, first recorded on 22 June 2023. Treat it as urgent.

**How severe is CVE-2020-35730?** Critical severity, with a CVSS score of 6.1, published 22 June 2023.

**Which products and versions are affected?** Roundcube Webmail before 1.2.13, 1.3.x before 1.3.16, 1.4.x before 1.4.10.

**Is there a fix for CVE-2020-35730?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2020-35730 attacked?** It is attacked over the network, in a web application.

**Am I affected by CVE-2020-35730?** Check whether you run Roundcube Webmail. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Affected products

- Roundcube Webmail before 1.2.13, 1.3.x before 1.3.16, 1.4.x before 1.4.10

## Timeline

- 2020-12-27: disclosed: Initial CVE assignment/disclosure date based on CVE ID year and external references
- 2023-06-22: kev added: Added to CISA Known Exploited Vulnerabilities Catalog
- 2023-06-22: exploited: Confirmed exploited in the wild per CISA KEV entry

## Related threats

- [Roundcube Webmail IMAP command injection in message cache](https://junglewise.ai/threats/cve-2026-126813-roundcube-webmail-before-1-6-21-and-1-7-x-before-1-7-6-contains)
- [Roundcube Webmail stored XSS in draft restore dialog subject field](https://junglewise.ai/threats/cve-2026-48849-roundcube-webmail-stored-xss-in-draft-restore-dialog-subject)
- [Roundcube Webmail remote image blocking bypass via CSS var()](https://junglewise.ai/threats/cve-2026-48846-roundcube-webmail-remote-image-blocking-bypass-via-css-var)
- [Roundcube Webmail SSRF via insufficient CSS sanitization](https://junglewise.ai/threats/cve-2026-48843-roundcube-webmail-ssrf-via-insufficient-css-sanitization)
- [Roundcube Webmail SQL Injection Vulnerability](https://junglewise.ai/threats/cve-2021-44026-roundcube-webmail-sql-injection-vulnerability)