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Known exploited · Roundcube

CVE-2023-43770: Roundcube Webmail Persistent Cross-Site Scripting (XSS) Vulnerability

What it is

Roundcube Webmail contains a persistent cross-site scripting (XSS) vulnerability that can lead to information disclosure via malicious link references in plain/text messages.

Added February 12, 2024Due March 4, 2024CISA KEV catalog 2026.10.01

Vendor
Roundcube
Product
Webmail
Added to KEV
February 12, 2024
CISA due date
March 4, 2024
Ransomware use
Unknown

What CISA requires

Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

Forensic triage

No

What to do now

  1. Find every instance of Webmail you run, including the forgotten ones, and check its version against the vendor advisory.
  2. Apply the vendor's fix or mitigation, before March 4, 2024 if you are bound by CISA's deadline, sooner if it faces the internet.
  3. Assume it was tried against you already: look for signs of exploitation from the date it was added, not from the day you patched.
  4. Until every instance is patched, block the attack at the edge: a WAF in blocking mode stops cross-site scripting payloads.

References

CVE-2023-43770 in the National Vulnerability Database

The Dome

Block it at the edge while you patch

The Dome's WAF runs the OWASP Core Rule Set in blocking mode and stops cross-site scripting payloads before they reach your application.

See the Dome

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Source: CISA Known Exploited Vulnerabilities Catalog (public domain), catalog version 2026.10.01.