Arbitrary bytecode execution via constant-pool truncation
Published Jul 19, 2022 · Updated May 27, 2026
Integer truncation in Apache Xalan-J 2.7.2 and earlier allows remote attackers to execute arbitrary Java bytecode via a malicious XSLT stylesheet. XSLTC lets BCEL's Java-array constant pool exceed the 65,535-entry class-file limit, then writes its length as a 16-bit value while serializing every entry. Execution requires an application to compile attacker-controlled XSLT; exposed SAML services are reachable when signature verification accepts XSLT transforms without an early trusted-key restriction.
Summary
What happened
Integer truncation in Apache Xalan-J 2.7.2 and earlier allows remote attackers to execute arbitrary Java bytecode via a malicious XSLT stylesheet. XSLTC lets BCEL's Java-array constant pool exceed the 65,535-entry class-file limit, then writes its length as a 16-bit value while serializing every entry. Execution requires an application to compile attacker-controlled XSLT; exposed SAML services are reachable when signature verification accepts XSLT transforms without an early trusted-key restriction.
The record
- CVE
- CVE-2022-34169
- Published
- Jul 19, 2022
- Updated
- May 27, 2026
- Vendor
- The Apache Software Foundation
- Product
- Apache Xalan-J
- Classifications
- CWE-681, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jul 19, 2022CVE publishedPublication date reported by the CVE source.
- May 27, 2026Record 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=Xalan-J <=2.7.2
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.
Weakness, pattern, technique
Public exploit references
- Project Zero XSLTC proof of conceptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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