Cross-user response disclosure via misplaced h2c leftover input
Published Mar 1, 2021 · Updated Feb 13, 2025
Information disclosure in Apache Tomcat allows remote attackers to read another user's request headers and body data via new h2c connections. The AbstractProtocol connection handler restored leftover input to the socket wrapper after releasing the HTTP/1.1 processor, allowing request bytes to cross connection boundaries. Exploitation requires new h2c connections and requests from different users to coincide; exposure is limited to duplicated headers, a limited body segment, and the resulting response.
Summary
What happened
Information disclosure in Apache Tomcat allows remote attackers to read another user's request headers and body data via new h2c connections. The AbstractProtocol connection handler restored leftover input to the socket wrapper after releasing the HTTP/1.1 processor, allowing request bytes to cross connection boundaries. Exploitation requires new h2c connections and requests from different users to coincide; exposure is limited to duplicated headers, a limited body segment, and the resulting response.
The record
- CVE
- CVE-2021-25122
- Published
- Mar 1, 2021
- Updated
- Feb 13, 2025
- Vendor
- The Apache Software Foundation
- Product
- Apache Tomcat
- Classifications
- CWE-200, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Mar 1, 2021CVE publishedPublication date reported by the CVE source.
- Feb 13, 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=Apache Tomcat 10 <10.0.2
- Affected versionversion=Apache Tomcat 8.5 <8.5.62
- Affected versionversion=Apache Tomcat 9 <9.0.42
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
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Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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