CVE-2025-1781: w3 Css Validator

Medium severity, CVSS 6.5. EPSS: 0.4% chance of exploitation in the next 30 days.

There is a XXE in W3CSS Validator versions before cssval-20250226 that allows an attacker to use specially-crafted XML objects to coerce server-side request forgery (SSRF).  This could be exploited to read arbitrary local files if an attacker has access to exception messages.

Affected products

• w3 Css Validator: before 20250226 (fixed in 20250226)

Published 2025-03-28. Last modified 2026-06-17.