Roundcube Webmail Cross-Site Scripting (XSS) Vulnerability
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.
- Vendor
- Roundcube
- Product
- Roundcube Webmail
- CVSS
- 6.1
- EPSS (exploit probability)
- 32.9%
- Status
- kev
- CISA patch-by (BOD 22-01)
- Added to KEV
Is CVE-2020-35730 being exploited?
Yes. CISA added CVE-2020-35730 to its Known Exploited Vulnerabilities catalog on . CISA only lists a CVE when it has reliable evidence of exploitation in the wild.
FIRST's EPSS model puts the probability of exploitation activity in the next 30 days at 32.9% (scored October 14, 2026).
- CISA KEV[ LISTED ]
- ENISA EUVD (exploited)[ — ]
- CIRCL KEV[ — ]
Catalog snapshot 2026-10-21. Full cross-catalog view: /kev-comparison
What to do
CISA required actionApply updates per vendor instructions.
US federal civilian agencies must remediate by (21 days after listing) under BOD 22-01. Everyone else: that deadline is a sensible upper bound, not a target. Vendor guidance and the NVD record are linked under Source above.
Other Roundcube Webmail CVEs we track
| CVE / Vulnerability | Severity | CVSS | EPSS | Added to KEV |
|---|---|---|---|---|
| CVE-2026-48842 Pre-auth SQL injection in Roundcube Webmail virtuser_query pluginwrite-up | [ HIGH ] | 8.1 | 0.9% | — |
| CVE-2025-68461 RoundCube Webmail Cross-site Scripting Vulnerability | [ HIGH ] | 7.2 | 26.8% | |
| CVE-2025-49113 Roundcube post-auth RCE via PHP object deserialization in upload handlerwrite-up | [ CRITICAL ] | 9.9 | 99.0% | |
| CVE-2024-42009 Roundcube stored XSS via crafted email runs attacker JavaScript in mailboxwrite-up | [ CRITICAL ] | 9.3 | 82.9% | |
| CVE-2024-37383 RoundCube Webmail Cross-Site Scripting (XSS) Vulnerability | [ MEDIUM ] | 6.1 | 73.3% | |
| CVE-2020-13965 Roundcube Webmail Cross-Site Scripting (XSS) Vulnerability | [ MEDIUM ] | 6.1 | 76.6% | |
| CVE-2023-43770 Roundcube Webmail Persistent Cross-Site Scripting (XSS) Vulnerability | [ MEDIUM ] | 6.1 | 63.7% | |
| CVE-2023-5631 Roundcube Webmail Persistent Cross-Site Scripting (XSS) Vulnerability | [ MEDIUM ] | 6.1 | 76.9% |