Cross-origin size disclosure via synthesized Range responses
Published Dec 22, 2022 · Updated Apr 15, 2025
Information disclosure in Firefox before 101, Firefox ESR before 91.10, and Thunderbird before 91.10 lets remote attackers infer resource sizes. A malicious site's service worker supplies an exaggerated Content-Range total, and the media loader trusts it when deciding whether to issue another Range request. A victim must load the site, and only the byte length of a Range-enabled cross-origin resource is disclosed.
Summary
What happened
Information disclosure in Firefox before 101, Firefox ESR before 91.10, and Thunderbird before 91.10 lets remote attackers infer resource sizes. A malicious site's service worker supplies an exaggerated Content-Range total, and the media loader trusts it when deciding whether to issue another Range request. A victim must load the site, and only the byte length of a Range-enabled cross-origin resource is disclosed.
The record
- CVE
- CVE-2022-31736
- Published
- Dec 22, 2022
- Updated
- Apr 15, 2025
- Vendor
- Mozilla
- Product
- Firefox
- Classifications
- CWE-942
- 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 <101
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
- Range and Service Worker resource-size oracle proof of conceptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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