CVE-2026-74998
High
Description
In Roundcube Webmail before 1.6.18 and 1.7.x before 1.7.3, responses from the CSS (Cascading Style Sheets) proxy were not validated, which may result in information disclosure or XSS (cross-site scripting) via MIME sniffing.
SeverityHigh
CVSS7.2
Exploit probability—
Product
Roundcube Webmail
PublishedAug 17, 2026
First seenAug 17, 2026
Weakness typeCWE-79Cross-site scripting (XSS)
How to fix
Update
- roundcube webmail1.6.18, 1.7.3 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| roundcube webmail | 1.6.0 ≤ v < 1.6.18, 1.7.0 ≤ v < 1.7.3 | 1.6.18, 1.7.3 |
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