CVE-2020-35730: in the CISA KEV catalogue
Roundcube Webmail Cross-Site Scripting (XSS) Vulnerability. CISA added CVE-2020-35730 to the Known Exploited Vulnerabilities catalogue on 2023-06-22 with a default due date of 2023-07-13. Known ransomware campaign use: Unknown. Forensic triage flag: No.
Roundcube Webmail contains a cross-site scripting (XSS) vulnerability that allows an attacker to send a plain text e-mail message with Javascript in a link reference element that is mishandled by linkref_addinindex in rcube_string_replacer.php. (CISA description)
- Vendor / product
- Roundcube Roundcube Webmail
- CWE
- CWE-79
- CISA required action
- Apply updates per vendor instructions.
- EPSS
- 33%, percentile 98 (scored 2026-11-03)
EPSS puts about 33 in 100 odds (33%) on exploitation activity being observed in the next 30 days. Its score is higher than or equal to that of 98% of scored CVEs. This is a model estimate about exploitation anywhere, not about your environment.
Vendor and reference links (from CISA)
Your own deadline under CISA BOD 26-04 depends on exposure, automatability and technical impact: work it out with the BOD 26-04 calculator.
Frequently asked questions
Is CVE-2020-35730 in the CISA KEV catalogue?
Yes. CISA added CVE-2020-35730 (Roundcube Webmail Cross-Site Scripting (XSS) Vulnerability) to the Known Exploited Vulnerabilities catalogue on 2023-06-22. CISA's default due date for it is 2023-07-13.
Is CVE-2020-35730 used in ransomware attacks?
CISA marks known ransomware campaign use as Unknown for CVE-2020-35730. That means CISA lacks confirmation, not that ransomware groups do not use it.
What should I do about CVE-2020-35730?
CISA's required action: Apply updates per vendor instructions.
Sources
- CISA, Known Exploited Vulnerabilities Catalog (accessed 2026-11-03)
- FIRST, Exploit Prediction Scoring System (EPSS) (EPSS by FIRST; scores generated by Empirical Security)
- NVD record for CVE-2020-35730