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Exploited. On CISA's list since 2023-10-26.
CVE-2023-5631 · Roundcube Webmail · Published 2023-10-18
5.4 out of 10
CVSS rates it medium.
76%
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 1079 days ago (2023-11-16).
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 allows a remote attacker to run malicious JavaScript code.
Roundcube before 1.4.15, 1.5.x before 1.5.5, and 1.6.x before 1.6.4 allows stored XSS via an HTML e-mail message with a crafted SVG document because of program/lib/Roundcube/rcube_washtml.php behavior. This could allow a remote attacker to load arbitrary JavaScript code.
From the NVD.
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Untrusted content becomes code running in another visitor's browser.
CWE-79 · CISA KEV; NVD record: nvd@nist.gov; NVD record: security@eset.com
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.