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Exploited. On CISA's list since 2024-02-12.
CVE-2023-43770 · Roundcube Webmail · Published 2023-09-22
6.1 out of 10
CVSS rates it medium.
64%
Estimated chance of exploitation in the next 30 days, among the top 1% of all scored flaws (EPSS, 2026-10-29).
Yes
CISA has seen it exploited in real attacks. For US government agencies the fix is deadline passed 970 days ago (2024-03-04).
Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
Roundcube Webmail contains a persistent cross-site scripting (XSS) vulnerability that can lead to information disclosure via malicious link references in plain/text messages.
Roundcube before 1.4.14, 1.5.x before 1.5.4, and 1.6.x before 1.6.3 allows XSS via text/plain e-mail messages with crafted links because of program/lib/Roundcube/rcube_string_replacer.php behavior.
From the NVD.
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Understand the kind of weakness behind this flaw. These resources teach the weakness, rather than reproduce this specific CVE. Follow the vendor's advice above to fix the affected product.
Untrusted content becomes code running in another visitor's browser.
CWE-79 · CISA KEV; NVD record: 134c704f-9b21-4f2e-91b3-4a467353bcc0; NVD record: nvd@nist.gov
Reading and practice labs · Free account for labs. Basic HTTP knowledge; some labs use Burp Suite.
CWE is a catalogue of weakness types. Labels come from the sources shown and can differ or change. Resource matches reviewed 16 October 2026.
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Exploited flaws from CISA's KEV catalogue. Chance of exploitation from EPSS by FIRST. Descriptions and scores from the NVD. This product uses the NVD API but is not endorsed or certified by the NVD.