CSP bypass via unsafe iframe policy inheritance
Published Jan 23, 2024 · Updated May 22, 2025
CSP bypass in Firefox before 122, Firefox ESR before 115.7, and Thunderbird before 115.7 allows remote attackers to run inline script via an iframe. Document::Open incorrectly treats the implicit document.open() from document.write() as a fresh about:blank navigation, discarding the child's meta CSP and inheriting the parent's unsafe-inline policy. Exploitation requires a user to load attacker-controlled framing content; Thunderbird disables scripting in mail, limiting exposure to browser-like contexts.
Summary
What happened
CSP bypass in Firefox before 122, Firefox ESR before 115.7, and Thunderbird before 115.7 allows remote attackers to run inline script via an iframe. Document::Open incorrectly treats the implicit document.open() from document.write() as a fresh about:blank navigation, discarding the child's meta CSP and inheriting the parent's unsafe-inline policy. Exploitation requires a user to load attacker-controlled framing content; Thunderbird disables scripting in mail, limiting exposure to browser-like contexts.
The record
- CVE
- CVE-2024-0747
- Published
- Jan 23, 2024
- Updated
- May 22, 2025
- Vendor
- Mozilla
- Product
- Firefox
- Classifications
- CWE-693, T1189
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jan 23, 2024CVE publishedPublication date reported by the CVE source.
- May 22, 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 <122
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
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.
Public exploit references
- Mozilla Bug 1764343 iframe CSP bypass reproducerproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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