CVE-2021-39144
Description
A flaw was found in xstream, a simple library used to serialize objects to XML and back again. This flaw allows a remote attacker to load and execute arbitrary code from a remote host by manipulating the processed input stream.
Statement
Users who follow the recommended security framework with a whitelist to limit the types to the minimum required should not be affected. XStream 1.4.18 no longer uses a blacklist by default since it cannot be secured for general purposes.
OpenShift Container Platform (OCP) delivers Jenkins LTS package with bundled XStream library. Due to JEP-200 [1] and JEP-228 [2] Jenkins projects, OCP Jenkins package is not affected by this flaw. This version of XStream library will be delivered in future Jenkins releases.
[1] https://github.com/jenkinsci/jep/blob/master/jep/200/README.adoc [2] https://github.com/jenkinsci/jep/blob/master/jep/228/README.adoc#security
For more information, please refer to the Red Hat solution Article explaining this issue.
OpenShift Logging's Elasticsearch 6.8.1 using opendistro_security v0.10.1.2 is not affected by the vulnerable code because com.thoughtworks.xstream is only a build-time dependency.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 8.5 | 8.5 | 8.5 |
| Attack Vector | Network | Network | Network |
| Attack Complexity | High | High | High |
| Privileges Required | Low | Low | Low |
| User Interaction | None | None | None |
| Scope | Changed | Changed | Changed |
| Confidentiality | High | High | High |
| Integrity Impact | High | High | High |
| Availability Impact | High | High | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
NVD: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
cve.org: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
Understanding the Weakness (CWE)
Integrity
Technical Impact: Modify Application Data; Unexpected State
Attackers can modify unexpected objects or data that was assumed to be safe from modification. Deserialized data or code could be modified without using the provided accessor functions, or unexpected functions could be invoked.
Availability
Technical Impact: DoS: Resource Consumption (CPU)
If a function is making an assumption on when to terminate, based on a sentry in a string, it could easily never terminate.
Other
Technical Impact: Varies by Context
The consequences can vary widely, because it depends on which objects or methods are being deserialized, and how they are used. Making an assumption that the code in the deserialized object is valid is dangerous and can enable exploitation. One example is attackers using gadget chains to perform unauthorized actions, such as generating a shell.
Frequently Asked Questions
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