CVE-2023-5631: in the CISA KEV catalogue
Roundcube Webmail Persistent Cross-Site Scripting (XSS) Vulnerability. CISA added CVE-2023-5631 to the Known Exploited Vulnerabilities catalogue on 2023-10-26 with a default due date of 2023-11-16. Known ransomware campaign use: Unknown. Forensic triage flag: No.
Roundcube Webmail contains a persistent cross-site scripting (XSS) vulnerability that allows a remote attacker to run malicious JavaScript code. (CISA description)
- Vendor / product
- Roundcube Webmail
- CWE
- CWE-79
- CISA required action
- Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
- EPSS
- 76%, percentile 99 (scored 2026-11-03)
EPSS puts about 76 in 100 odds (76%) on exploitation activity being observed in the next 30 days. Its score is higher than or equal to that of 99% 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-2023-5631 in the CISA KEV catalogue?
Yes. CISA added CVE-2023-5631 (Roundcube Webmail Persistent Cross-Site Scripting (XSS) Vulnerability) to the Known Exploited Vulnerabilities catalogue on 2023-10-26. CISA's default due date for it is 2023-11-16.
Is CVE-2023-5631 used in ransomware attacks?
CISA marks known ransomware campaign use as Unknown for CVE-2023-5631. That means CISA lacks confirmation, not that ransomware groups do not use it.
What should I do about CVE-2023-5631?
CISA's required action: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
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-2023-5631