CVE-2021-39146Public exploitNetwork attack vector

Code execution via attacker-controlled type reconstruction

Published Aug 23, 2021 · Updated Aug 4, 2024

Unsafe deserialization in XStream before 1.4.18 allows remote authenticated users to execute arbitrary code via crafted input. During unmarshalling, XStream trusts attacker-supplied type information, instantiates injected JDK objects, and invokes a JNDI lookup that loads code from an LDAP server. Exposure requires an application to pass attacker-controlled data to XStream without a minimal type allowlist; successful execution runs with that application's privileges.

CVSS severity8.5
High
EPSS probability14.30%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Unsafe deserialization in XStream before 1.4.18 allows remote authenticated users to execute arbitrary code via crafted input. During unmarshalling, XStream trusts attacker-supplied type information, instantiates injected JDK objects, and invokes a JNDI lookup that loads code from an LDAP server. Exposure requires an application to pass attacker-controlled data to XStream without a minimal type allowlist; successful execution runs with that application's privileges.

The record

CVE
CVE-2021-39146
Published
Aug 23, 2021
Updated
Aug 4, 2024
Vendor
XStream
Product
XStream
Classifications
CWE-502
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 23, 2021CVE publishedPublication date reported by the CVE source.
  2. 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.

  1. Affected versionversion=< 1.4.18

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

XStream · XStreamversion=< 1.4.18

Published CVSS scores

6.0NVDAV:N/AC:M/Au:S/C:P/I:P/A:P
8.5GitHubCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-502Deserialization of Untrusted Data

Public exploit references

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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