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A Server-Side Forgery Request can be activated unmarshalling with XStream to access data streams from an arbitrary URL referencing a resource in an intranet or the local host

Moderate severity GitHub Reviewed Published Mar 13, 2021 in x-stream/xstream • Updated Mar 9, 2023

Package

maven com.thoughtworks.xstream:xstream (Maven)

Affected versions

< 1.4.16

Patched versions

1.4.16

Description

Impact

The processed stream at unmarshalling time contains type information to recreate the formerly written objects. XStream creates therefore new instances based on these type information. An attacker can manipulate the processed input stream and replace or inject objects, that result in a server-side forgery request. No user is affected, who followed the recommendation to setup XStream's security framework with a whitelist limited to the minimal required types.

Patches

If you rely on XStream's default blacklist of the Security Framework, you will have to use at least version 1.4.16

Workarounds

See workarounds for the different versions covering all CVEs.

References

See full information about the nature of the vulnerability and the steps to reproduce it in XStream's documentation for CVE-2021-21342.

Credits

钟潦贵 (Liaogui Zhong) found and reported the issue to XStream and provided the required information to reproduce it.

For more information

If you have any questions or comments about this advisory:

References

@joehni joehni published to x-stream/xstream Mar 13, 2021
Reviewed Mar 22, 2021
Published to the GitHub Advisory Database Mar 22, 2021
Published by the National Vulnerability Database Mar 23, 2021
Last updated Mar 9, 2023

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
High
Privileges required
None
User interaction
Required
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N

EPSS score

0.973%
(84th percentile)

Weaknesses

CVE ID

CVE-2021-21342

GHSA ID

GHSA-hvv8-336g-rx3m

Source code

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