Remote code execution via injected SEIStub object graph
Published Aug 23, 2021 · Updated Aug 4, 2024
Deserialization in XStream 1.4.17 and earlier allows remote authenticated users to execute arbitrary code via a crafted input stream. During unmarshalling, attacker-controlled type metadata builds a PriorityQueue and dynamic proxy using SEIStub, causing InitialContext.doLookup to fetch and run code from an LDAP server. Exploitation requires an application to unmarshal attacker-controlled data with the default blacklist; a minimal type allowlist prevents the gadget graph from being instantiated.
Summary
What happened
Deserialization in XStream 1.4.17 and earlier allows remote authenticated users to execute arbitrary code via a crafted input stream. During unmarshalling, attacker-controlled type metadata builds a PriorityQueue and dynamic proxy using SEIStub, causing InitialContext.doLookup to fetch and run code from an LDAP server. Exploitation requires an application to unmarshal attacker-controlled data with the default blacklist; a minimal type allowlist prevents the gadget graph from being instantiated.
The record
- CVE
- CVE-2021-39141
- Published
- Aug 23, 2021
- Updated
- Aug 4, 2024
- Vendor
- XStream
- Product
- XStream
- Classifications
- CWE-502, CWE-434, T1203
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Aug 23, 2021CVE publishedPublication date reported by the CVE source.
- Aug 4, 2024Record 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=< 1.4.18
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
- XStream SEIStub deserialization proof of conceptproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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