Cross-site information leak via CSP base bypass
Published Dec 22, 2022 · Updated Apr 15, 2025
CSP bypass in Mozilla Firefox before 105, Firefox ESR before 102.3, and Thunderbird before 102.3 allows remote attackers to leak URL paths. The speculative HTML parser accepts an injected base element for some image requests instead of enforcing the page's CSP base-uri restriction. Exploitation requires attacker-controlled HTML injection and a user to load the affected content; the resulting cross-site request exposes otherwise secret URL path components.
Summary
What happened
CSP bypass in Mozilla Firefox before 105, Firefox ESR before 102.3, and Thunderbird before 102.3 allows remote attackers to leak URL paths. The speculative HTML parser accepts an injected base element for some image requests instead of enforcing the page's CSP base-uri restriction. Exploitation requires attacker-controlled HTML injection and a user to load the affected content; the resulting cross-site request exposes otherwise secret URL path components.
The record
- CVE
- CVE-2022-40956
- Published
- Dec 22, 2022
- Updated
- Apr 15, 2025
- Vendor
- Mozilla
- Product
- Firefox
- Classifications
- CWE-79
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Dec 22, 2022CVE publishedPublication date reported by the CVE source.
- Apr 15, 2025Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=unspecified <105
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- Mozilla Bugzilla CSP base-uri bypass testcaseproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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