Content security policy: allows untrusted style execution

Description: Content security policy: allows untrusted style execution

Content Security Policy (CSP) is a security mechanism designed to mitigate cross-site scripting attacks by disabling dangerous behaviours such as untrusted JavaScript execution. Websites can specify their security policy in a response header or meta tag, enabling fine-grained control over dangerous features like scripts and stylesheets.

Remediation: Content security policy: allows untrusted style execution

Mitigate style-based data exfiltration by avoiding 'unsafe-inline', data: URLs, and global wildcards in style directives. Use a secure, random nonce of at least 8 characters 'nonce-RANDOM' in the relevant directive.

References

• Web Security Academy: What is CSP?
• PortSwigger Research: Blind CSS exfiltration
• PortSwigger Research: Offensive CSS research
• Content Security Policy (CSP)

Vulnerability classifications

• CWE-116: Improper Encoding or Escaping of Output
• CWE-159: Failure to Sanitize Special Element
• CAPEC-468: Generic Cross-Browser Cross-Domain Theft

Typical severity

Information

Type index (hex)

0x00200505

Type index (decimal)

2098437