This vulnerability in Roundcube Webmail is due to improper neutralization of input during web page generation (CWE-79). Specifically, the HTML content of attachments is not sufficiently sanitized when previewed, enabling cross-site scripting attacks. The affected versions are all releases before 1.5.14 and 1.6.14. The CVSS 3.1 base score is 6.1, reflecting network attack vector, low attack complexity, no privileges required, user interaction required, scope changed, and partial confidentiality and integrity impacts.

Successful exploitation allows an attacker to execute arbitrary scripts in the context of the victim's browser session when previewing a malicious HTML attachment. This can lead to partial disclosure of information and modification of data accessible to the user. There is no impact on system availability. No known exploits are reported in the wild at this time.

Patch status is not yet confirmed — no official fix or vendor advisory is provided in the available data. Users should monitor the Roundcube project for updates addressing this vulnerability. Until a patch is available, avoid previewing untrusted HTML attachments to mitigate risk.