Information exposure via CSS variable filter bypass
Published Apr 30, 2024 · Updated Mar 14, 2025
Information exposure in CSS Exfil Protection 1.1.0 allows remote attackers to leak page data through attacker-controlled CSS. The parseCSSRules() filter checks selectors and URL values only when they share one CSSStyleRule, so CSS variables can separate an exfiltration selector from its outbound URL and bypass sanitization. No authentication is required, but crafted CSS must be processed in a page where the extension is relied upon to block CSS exfiltration.
Summary
What happened
Information exposure in CSS Exfil Protection 1.1.0 allows remote attackers to leak page data through attacker-controlled CSS. The parseCSSRules() filter checks selectors and URL values only when they share one CSSStyleRule, so CSS variables can separate an exfiltration selector from its outbound URL and bypass sanitization. No authentication is required, but crafted CSS must be processed in a page where the extension is relied upon to block CSS exfiltration.
The record
- CVE
- CVE-2024-33436
- Published
- Apr 30, 2024
- Updated
- Mar 14, 2025
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- CWE-200
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Apr 30, 2024CVE publishedPublication date reported by the CVE source.
- Mar 14, 2025Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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What is affected?
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Published CVSS scores
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Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
- CSS Exfil Protection CSS-variable bypass proof of conceptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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