Which versions of Css Validator are affected by CVE-2025-1781?

Organizations using W3CSS Validator face notable risk from CVE-2025-1781, a XML external entity vulnerability rated CVSS 8.4.

Is there a public PoC exploit available for CVE-2025-1781?

Yes, a public proof-of-concept exploit is available for CVE-2025-1781. Prioritise patching immediately. EPSS: 0.2%.

How to fix or mitigate CVE-2025-1781?

Within 7 days: Identify all affected systems running W3CSS Validator and apply vendor patches promptly. Monitor vendor channels for patch availability.

Css Validator CVE-2025-1781

Q: What is the CVSS score of CVE-2025-1781?

CVE-2025-1781 has a CVSS 4.0 base score of 8.4 (High). CVSS vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:L/SC:N/SI:H/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X. EPSS exploitation probability: 0.2%.

HIGH

Improper Restriction of XML External Entity Reference (CWE-611)

2025-03-28 cve-coordination@google.com

XXE SSRF Css Validator

8.4

CVSS 4.0 · NVD

Severity by source

NVD PRIMARY

8.4 HIGH

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:L/SC:N/SI:H/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:L/SC:N/SI:H/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Lifecycle Timeline

Analysis Generated

Mar 28, 2026 - 18:33 vuln.today

PoC Detected

Aug 01, 2025 - 17:54 vuln.today

Public exploit code

CVE Published

Mar 28, 2025 - 14:15 nvd

HIGH 8.4

DescriptionCVE.org

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.

AnalysisAI

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). Rated high severity (CVSS 8.4), this vulnerability is remotely exploitable, low attack complexity. Public exploit code available and no vendor patch available.

Technical ContextAI

This vulnerability is classified as XML External Entity (XXE) (CWE-611), which allows attackers to read arbitrary files or perform SSRF through XML processing. 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 include: W3 Css Validator.

RemediationAI

No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Disable external entity processing in XML parsers, use JSON instead of XML where possible.

CVE-2025-1781 vulnerability details – vuln.today

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