CVE-2021-21349: Xstream Remote Code Execution Vulnerability

MODERATE
Advisory Identifier: GHSA-f6hm-88x3-mfjv
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CVSS 6.1
CWE-502 CWE-918
Published
Advisory Summary

CVE-2021-21349 is a MODERATE (CVSS 6.1) remote code execution vulnerability (CWE-502: Deserialization of Untrusted Data) affecting Xstream libraries in the Maven ecosystem. The issue involves 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. Remediation is available by upgrading affected packages to version 1.4.16.

CVE-2021-21349 at a Glance

CVE Identifier CVE-2021-21349
GHSA Identifier GHSA-f6hm-88x3-mfjv
Severity MODERATE
CVSS v3.1 Base Score 6.1
CWE Classification CWE-502: Deserialization of Untrusted Data
Affected Product Xstream
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 6.1

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:N/I:H/A:N).

Attack Vector Network (AV:N)
Attack Complexity High (AC:H)
Privileges Required None (PR:N)
User Interaction Required (UI:R)
Scope Changed (S:C)
Confidentiality None (C:N)
Integrity High (I:H)
Availability None (A:N)

How to Fix CVE-2021-21349

To remediate this vulnerability, upgrade all affected Xstream dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

com.thoughtworks.xstream:xstream fixed: 1.4.16 
<dependency>
    <groupId>com.thoughtworks.xstream</groupId>
    <artifactId>xstream</artifactId>
    <version>1.4.16</version>
</dependency>
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

mvn dependency:tree -Dincludes=com.thoughtworks.xstream

How to Check if You Are Affected

To determine whether your Java application is affected by CVE-2021-21349, inspect your build dependencies using the Maven Dependency Plugin:

mvn dependency:tree -Dincludes=com.thoughtworks.xstream

Analyze the terminal output to locate any version of Xstream in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.4.16), your application is affected.

Note: The mvn dependency:tree -Dincludes=com.thoughtworks.xstream command inspects the resolved dependency graph declared in your project's POM files; it does not perform automated security scanning or inspect runtime dynamic classpaths. Always verify runtime container classpaths and shaded JARs.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-502: Deserialization of Untrusted Data, where the product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid. In Xstream, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Impact The vulnerability may allow a remote attacker to request data from internal resources that are not publicly available only by manipulating the processed input stream. 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](https://x-stream.github.io/security.html#framework), you will have to use at least version 1.4.16. ### Workarounds See [workarounds](https://x-stream.github.io/security.html#workaround) 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-2021-21349](https://x-stream.github.io/CVE-2021-21349.html). ### Credits The vulnerability was discovered and reported by threedr3am. ### For more information If you have any questions or comments about this advisory: * Open an issue in [XStream](https://github.com/x-stream/xstream/issues) * Contact us at [XStream Google Group](https://groups.google.com/group/xstream-user)

CVE-2021-21349 Affected Xstream Versions

1 component(s)
Fixed Versions:
1.4.16
Product / Package Ecosystem Affected Versions Fixed Version
com.thoughtworks.xstream:xstream
maven/com.thoughtworks.xstream/xstream
Maven
< 1.4.16
1.4.16

References

GitHub Advisory / Wiki ADVISORY
https://github.com/x-stream/xstream/security/advisories/GHSA-f6hm-88x3-mfjv
NVD — CVE-2021-21349 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-21349
Xstream Source Repository REPOSITORY
https://github.com/x-stream/xstream
lists.apache.org/thread.html/r8244fd... WEB
https://lists.apache.org/thread.html/r8244fd0831db894d5e89911ded9c72196d395a90ae655414d23ed0dd@%3Cusers.activemq.apache.org%3E
lists.apache.org/thread.html/r9ac71b... WEB
https://lists.apache.org/thread.html/r9ac71b047767205aa22e3a08cb33f3e0586de6b2fac48b425c6e16b0@%3Cdev.jmeter.apache.org%3E
lists.debian.org/debian-lts-announce... WEB
https://lists.debian.org/debian-lts-announce/2021/04/msg00002.html
lists.fedoraproject.org/archives/list/packa... WEB
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/22KVR6B5IZP3BGQ3HPWIO2FWWCKT3DHP
lists.fedoraproject.org/archives/list/packa... WEB
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/PVPHZA7VW2RRSDCOIPP2W6O5ND254TU7
lists.fedoraproject.org/archives/list/packa... WEB
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/QGXIU3YDPG6OGTDHMBLAFN7BPBERXREB
Xstream Security Information SECURITY
https://security.netapp.com/advisory/ntap-20210430-0002
Xstream Security Information SECURITY
https://www.debian.org/security/2021/dsa-5004
Xstream Security Information SECURITY
https://www.oracle.com//security-alerts/cpujul2021.html
Xstream Security Information SECURITY
https://www.oracle.com/security-alerts/cpujan2022.html
Xstream Security Information SECURITY
https://www.oracle.com/security-alerts/cpuoct2021.html
x-stream.github.io/cve-2021-21349.html WEB
https://x-stream.github.io/CVE-2021-21349.html
Xstream Security Information SECURITY
https://x-stream.github.io/security.html#workaround
x-stream.github.io/changes.html WEB
http://x-stream.github.io/changes.html#1.4.16

Frequently Asked Questions

What is CVE-2021-21349?
CVE-2021-21349 is a security vulnerability in Xstream involving 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 under CWE-502: Deserialization of Untrusted Data.
Which Xstream versions are affected?
Affected versions include releases prior to 1.4.16 across affected packages: com.thoughtworks.xstream:xstream.
What version fixes CVE-2021-21349?
Upgrading to 1.4.16 (or the latest patched release for your respective branch) resolves the vulnerability.
Is xstream affected?
Yes, com.thoughtworks.xstream:xstream is affected in releases prior to 1.4.16. Upgrade your dependency to 1.4.16 or later.
What is the CVSS score of CVE-2021-21349?
CVE-2021-21349 has a CVSS v3.1 base score of 6.1 (MODERATE) with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:N/I:H/A:N.
What CWE is associated with CVE-2021-21349?
CVE-2021-21349 is classified under CWE-502: Deserialization of Untrusted Data (The product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid.).
How can I check Maven dependencies for CVE-2021-21349?
Run the dependency tree command: 'mvn dependency:tree -Dincludes=com.thoughtworks.xstream'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-f6hm-88x3-mfjv",
  "modified" : "2022-02-08T21:32:19Z",
  "published" : "2021-03-22T23:29:19Z",
  "aliases" : [ "CVE-2021-21349" ],
  "summary" : "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",
  "details" : "### Impact\nThe vulnerability may allow a remote attacker to request data from internal resources that are not publicly available only by manipulating the processed input stream. No user is affected, who followed the recommendation to setup XStream's security framework with a whitelist limited to the minimal required types.\n\n### Patches\nIf you rely on XStream's default blacklist of the [Security Framework](https://x-stream.github.io/security.html#framework), you will have to use at least version 1.4.16.\n\n### Workarounds\nSee [workarounds](https://x-stream.github.io/security.html#workaround) for the different versions covering all CVEs.\n\n### References\nSee full information about the nature of the vulnerability and the steps to reproduce it in XStream's documentation for [CVE-2021-21349](https://x-stream.github.io/CVE-2021-21349.html).\n\n### Credits\nThe vulnerability was discovered and reported by threedr3am.\n\n### For more information\nIf you have any questions or comments about this advisory:\n* Open an issue in [XStream](https://github.com/x-stream/xstream/issues)\n* Contact us at [XStream Google Group](https://groups.google.com/group/xstream-user)",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:N/I:H/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "com.thoughtworks.xstream:xstream"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.4.16"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/x-stream/xstream/security/advisories/GHSA-f6hm-88x3-mfjv"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-21349"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/x-stream/xstream"
  }, {
    "type" : "WEB",
    "url" : "https://lists.apache.org/thread.html/r8244fd0831db894d5e89911ded9c72196d395a90ae655414d23ed0dd@%3Cusers.activemq.apache.org%3E"
  }, {
    "type" : "WEB",
    "url" : "https://lists.apache.org/thread.html/r9ac71b047767205aa22e3a08cb33f3e0586de6b2fac48b425c6e16b0@%3Cdev.jmeter.apache.org%3E"
  }, {
    "type" : "WEB",
    "url" : "https://lists.debian.org/debian-lts-announce/2021/04/msg00002.html"
  }, {
    "type" : "WEB",
    "url" : "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/22KVR6B5IZP3BGQ3HPWIO2FWWCKT3DHP"
  }, {
    "type" : "WEB",
    "url" : "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/PVPHZA7VW2RRSDCOIPP2W6O5ND254TU7"
  }, {
    "type" : "WEB",
    "url" : "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/QGXIU3YDPG6OGTDHMBLAFN7BPBERXREB"
  }, {
    "type" : "WEB",
    "url" : "https://security.netapp.com/advisory/ntap-20210430-0002"
  }, {
    "type" : "WEB",
    "url" : "https://www.debian.org/security/2021/dsa-5004"
  }, {
    "type" : "WEB",
    "url" : "https://www.oracle.com//security-alerts/cpujul2021.html"
  }, {
    "type" : "WEB",
    "url" : "https://www.oracle.com/security-alerts/cpujan2022.html"
  }, {
    "type" : "WEB",
    "url" : "https://www.oracle.com/security-alerts/cpuoct2021.html"
  }, {
    "type" : "WEB",
    "url" : "https://x-stream.github.io/CVE-2021-21349.html"
  }, {
    "type" : "WEB",
    "url" : "https://x-stream.github.io/security.html#workaround"
  }, {
    "type" : "WEB",
    "url" : "http://x-stream.github.io/changes.html#1.4.16"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-502", "CWE-918" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-03-22T23:26:25Z",
    "nvd_published_at" : "2021-03-23T00:15:00Z"
  }
}