Cross-origin data disclosure via redirected PDF ranges
Published Feb 26, 2021 · Updated Aug 3, 2024
Cross-origin information disclosure in Mozilla Firefox before 85, Firefox ESR before 78.7, and Thunderbird before 78.7 allows remote attackers to read data. PDF.js accepts redirected HTTP 206 range responses from a different origin without validating each response URL before combining PDF chunks. Exploitation requires a user click, a range-capable target server, and attacker-controlled redirects; the consequence is cross-origin data disclosure.
Summary
What happened
Cross-origin information disclosure in Mozilla Firefox before 85, Firefox ESR before 78.7, and Thunderbird before 78.7 allows remote attackers to read data. PDF.js accepts redirected HTTP 206 range responses from a different origin without validating each response URL before combining PDF chunks. Exploitation requires a user click, a range-capable target server, and attacker-controlled redirects; the consequence is cross-origin data disclosure.
The record
- CVE
- CVE-2021-23953
- Published
- Feb 26, 2021
- Updated
- Aug 3, 2024
- Vendor
- Mozilla
- Product
- Firefox
- Classifications
- T1189
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Feb 26, 2021CVE publishedPublication date reported by the CVE source.
- Aug 3, 2024Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 85
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
- Redirected PDF range-request reproductionproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
Check the software in your environment
Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.
Book a demo