CVE-2020-26258: Xstream Server-Side Forgery Request Can Be Vulnerability

Q: What is CVE-2020-26258?

CVE-2020-26258 is a security vulnerability in Xstream involving Server-Side Forgery Request can be activated unmarshalling with XStream under CWE-918: Server-Side Request Forgery (SSRF).

Q: Which Xstream versions are affected?

Affected versions include releases prior to 1.4.15 across affected packages: com.thoughtworks.xstream:xstream.

Q: What version fixes CVE-2020-26258?

Upgrading to 1.4.15 (or the latest patched release for your respective branch) resolves the vulnerability.

Q: Is xstream affected?

Yes, com.thoughtworks.xstream:xstream is affected in releases prior to 1.4.15. Upgrade your dependency to 1.4.15 or later.

Q: What is the CVSS score of CVE-2020-26258?

CVE-2020-26258 has a CVSS v3.1 base score of 6.3 (MODERATE) with vector string CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N.

Q: What CWE is associated with CVE-2020-26258?

CVE-2020-26258 is classified under CWE-918: Server-Side Request Forgery (SSRF) (The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.).

Q: How can I check Maven dependencies for CVE-2020-26258?

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.

MODERATE

Advisory Identifier: GHSA-4cch-wxpw-8p28

CVSS 6.3

CWE-918

Published 2020-12-21

Advisory Summary

CVE-2020-26258 is a MODERATE (CVSS 6.3) server-side forgery request can be vulnerability (CWE-918: Server-Side Request Forgery (SSRF)) affecting Xstream libraries in the Maven ecosystem. The issue involves server-side forgery request can be activated unmarshalling with xstream. Remediation is available by upgrading affected packages to version 1.4.15.

CVE-2020-26258 at a Glance

CVE Identifier CVE-2020-26258

GHSA Identifier GHSA-4cch-wxpw-8p28

Severity MODERATE

CVSS v3.1 Base Score 6.3

CWE Classification CWE-918: Server-Side Request Forgery (SSRF)

Affected Product Xstream

Package Ecosystem Maven

Published Date 2020-12-21

Last Updated 2025-01-15

Security Impact

CVSS: 6.3

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

Attack Vector Network (AV:N)

Attack Complexity High (AC:H)

Privileges Required Low (PR:L)

User Interaction None (UI:N)

Scope Changed (S:C)

Confidentiality High (C:H)

Integrity None (I:N)

Availability None (A:N)

How to Fix CVE-2020-26258

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: 1.4.15

<dependency>
    <groupId>com.thoughtworks.xstream</groupId>
    <artifactId>xstream</artifactId>
    <version>1.4.15</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-2020-26258, 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 1.4.15), 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-918: Server-Side Request Forgery (SSRF), where the web server receives a url or similar request from an upstream component and retrieves the contents of this url, but it does not sufficiently ensure that the request is being sent to the expected destination. 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. ### 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 1.4.15. ### Workarounds The reported vulnerability does not exist running Java 15 or higher. No user is affected, who followed the recommendation to setup XStream's Security Framework with a whitelist! Anyone relying on XStream's default blacklist can immediately switch to a whilelist for the allowed types to avoid the vulnerability. Users of XStream 1.4.14 or below who still insist to use XStream default blacklist - despite that clear recommendation - can use a workaround depending on their version in use. Users of XStream 1.4.14 can simply add two lines to XStream's setup code: ```Java xstream.denyTypes(new String[]{ "jdk.nashorn.internal.objects.NativeString" }); xstream.denyTypesByRegExp(new String[]{ ".*\\.ReadAllStream\\$FileStream" }); ``` Users of XStream 1.4.14 to 1.4.13 can simply add three lines to XStream's setup code: ```Java xstream.denyTypes(new String[]{ "javax.imageio.ImageIO$ContainsFilter", "jdk.nashorn.internal.objects.NativeString" }); xstream.denyTypes(new Class[]{ java.lang.ProcessBuilder.class }); xstream.denyTypesByRegExp(new String[]{ ".*\\.ReadAllStream\\$FileStream" }); ``` Users of XStream 1.4.12 to 1.4.7 who want to use XStream with a black list will have to setup such a list from scratch and deny at least the following types: _javax.imageio.ImageIO$ContainsFilter_, _java.beans.EventHandler_, _java.lang.ProcessBuilder_, _jdk.nashorn.internal.objects.NativeString.class_, _java.lang.Void_ and _void_ and deny several types by name pattern. ```Java xstream.denyTypes(new String[]{ "javax.imageio.ImageIO$ContainsFilter", "jdk.nashorn.internal.objects.NativeString" }); xstream.denyTypes(new Class[]{ java.lang.ProcessBuilder.class, "jdk.nashorn.internal.objects.NativeString", java.beans.EventHandler.class, java.lang.ProcessBuilder.class, java.lang.Void.class, void.class }); xstream.denyTypesByRegExp(new String[]{ ".*\\$LazyIterator", "javax\\.crypto\\..*", ".*\\.ReadAllStream\\$FileStream" }); ``` Users of XStream 1.4.6 or below can register an own converter to prevent the unmarshalling of the currently know critical types of the Java runtime. It is in fact an updated version of the workaround for CVE-2013-7285: ```Java xstream.registerConverter(new Converter() { public boolean canConvert(Class type) { return type != null && (type == java.beans.EventHandler.class || type == java.lang.ProcessBuilder.class || type.getName().equals("javax.imageio.ImageIO$ContainsFilter") || type.getName().equals("jdk.nashorn.internal.objects.NativeString") || type == java.lang.Void.class || void.class || Proxy.isProxy(type)) || type.getName().startsWith("javax.crypto.") || type.getName().endsWith("$LazyIterator") || type.getName().endsWith(".ReadAllStream$FileStream")); } public Object unmarshal(HierarchicalStreamReader reader, UnmarshallingContext context) { throw new ConversionException("Unsupported type due to security reasons."); } public void marshal(Object source, HierarchicalStreamWriter writer, MarshallingContext context) { throw new ConversionException("Unsupported type due to security reasons."); } }, XStream.PRIORITY_LOW); ``` ### 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-2020-26258 Affected Xstream Versions

1 component(s)

Fixed Versions:

1.4.15

Product / Package	Ecosystem	Affected Versions	Fixed Version
com.thoughtworks.xstream:xstream maven/com.thoughtworks.xstream/xstream	Maven	< 1.4.15	1.4.15

References

GitHub Advisory / Wiki ADVISORY

https://github.com/x-stream/xstream/security/advisories/GHSA-4cch-wxpw-8p28

NVD — CVE-2020-26258 NVD

https://nvd.nist.gov/vuln/detail/CVE-2020-26258

Xstream Source Repository REPOSITORY

https://github.com/x-stream/xstream

lists.apache.org/thread.html/r97993e... WEB

https://lists.apache.org/thread.html/r97993e3d78e1f5389b7b172ba9f308440830ce5f051ee62714a0aa34%40%3Ccommits.struts.apache.org%3E

lists.apache.org/thread.html/r97993e... WEB

https://lists.apache.org/thread.html/r97993e3d78e1f5389b7b172ba9f308440830ce5f051ee62714a0aa34@%3Ccommits.struts.apache.org%3E

lists.debian.org/debian-lts-announce... WEB

https://lists.debian.org/debian-lts-announce/2020/12/msg00042.html

lists.fedoraproject.org/archives/list/packa... WEB

https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/22KVR6B5IZP3BGQ3HPWIO2FWWCKT3DHP

lists.fedoraproject.org/archives/list/packa... WEB

https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PVPHZA7VW2RRSDCOIPP2W6O5ND254TU7

lists.fedoraproject.org/archives/list/packa... WEB

https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QGXIU3YDPG6OGTDHMBLAFN7BPBERXREB

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-20210409-0005

Xstream Security Information SECURITY

https://www.debian.org/security/2021/dsa-4828

x-stream.github.io/cve-2020-26258.html WEB

https://x-stream.github.io/CVE-2020-26258.html

Frequently Asked Questions

What is CVE-2020-26258?

CVE-2020-26258 is a security vulnerability in Xstream involving Server-Side Forgery Request can be activated unmarshalling with XStream under CWE-918: Server-Side Request Forgery (SSRF).

Which Xstream versions are affected?

Affected versions include releases prior to 1.4.15 across affected packages: com.thoughtworks.xstream:xstream.

What version fixes CVE-2020-26258?

Upgrading to 1.4.15 (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 1.4.15. Upgrade your dependency to 1.4.15 or later.

What is the CVSS score of CVE-2020-26258?

CVE-2020-26258 has a CVSS v3.1 base score of 6.3 (MODERATE) with vector string CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N.

What CWE is associated with CVE-2020-26258?

CVE-2020-26258 is classified under CWE-918: Server-Side Request Forgery (SSRF) (The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.).

How can I check Maven dependencies for CVE-2020-26258?

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-4cch-wxpw-8p28",
  "modified" : "2025-01-15T21:31:38Z",
  "published" : "2020-12-21T16:28:42Z",
  "aliases" : [ "CVE-2020-26258" ],
  "summary" : "Server-Side Forgery Request can be activated unmarshalling with XStream",
  "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.\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 1.4.15.\n\n### Workarounds\nThe reported vulnerability does not exist running Java 15 or higher.\n\nNo user is affected, who followed the recommendation to setup XStream's Security Framework with a whitelist! Anyone relying on XStream's default blacklist can immediately switch to a whilelist for the allowed types to avoid the vulnerability.\n\nUsers of XStream 1.4.14 or below who still insist to use XStream default blacklist - despite that clear recommendation - can use a workaround depending on their version in use.\n\nUsers of XStream 1.4.14 can simply add two lines to XStream's setup code:\n```Java\nxstream.denyTypes(new String[]{ \"jdk.nashorn.internal.objects.NativeString\" });\nxstream.denyTypesByRegExp(new String[]{ \".*\\\\.ReadAllStream\\\\$FileStream\" });\n```\n\nUsers of XStream 1.4.14 to 1.4.13 can simply add three lines to XStream's setup code:\n```Java\nxstream.denyTypes(new String[]{ \"javax.imageio.ImageIO$ContainsFilter\", \"jdk.nashorn.internal.objects.NativeString\" });\nxstream.denyTypes(new Class[]{ java.lang.ProcessBuilder.class });\nxstream.denyTypesByRegExp(new String[]{ \".*\\\\.ReadAllStream\\\\$FileStream\" });\n```\nUsers of XStream 1.4.12 to 1.4.7 who want to use XStream with a black list will have to setup such a list from scratch and deny at least the following types: _javax.imageio.ImageIO$ContainsFilter_, _java.beans.EventHandler_, _java.lang.ProcessBuilder_, _jdk.nashorn.internal.objects.NativeString.class_, _java.lang.Void_ and _void_ and deny several types by name pattern.\n```Java\nxstream.denyTypes(new String[]{ \"javax.imageio.ImageIO$ContainsFilter\", \"jdk.nashorn.internal.objects.NativeString\" });\nxstream.denyTypes(new Class[]{ java.lang.ProcessBuilder.class, \"jdk.nashorn.internal.objects.NativeString\", java.beans.EventHandler.class, java.lang.ProcessBuilder.class, java.lang.Void.class, void.class });\nxstream.denyTypesByRegExp(new String[]{ \".*\\\\$LazyIterator\", \"javax\\\\.crypto\\\\..*\", \".*\\\\.ReadAllStream\\\\$FileStream\" });\n```\nUsers of XStream 1.4.6 or below can register an own converter to prevent the unmarshalling of the currently know critical types of the Java runtime. It is in fact an updated version of the workaround for CVE-2013-7285:\n```Java\nxstream.registerConverter(new Converter() {\n  public boolean canConvert(Class type) {\n    return type != null && (type == java.beans.EventHandler.class || type == java.lang.ProcessBuilder.class\n        || type.getName().equals(\"javax.imageio.ImageIO$ContainsFilter\") || type.getName().equals(\"jdk.nashorn.internal.objects.NativeString\")\n        || type == java.lang.Void.class || void.class || Proxy.isProxy(type))\n        || type.getName().startsWith(\"javax.crypto.\") || type.getName().endsWith(\"$LazyIterator\") || type.getName().endsWith(\".ReadAllStream$FileStream\"));\n  }\n\n  public Object unmarshal(HierarchicalStreamReader reader, UnmarshallingContext context) {\n    throw new ConversionException(\"Unsupported type due to security reasons.\");\n  }\n\n  public void marshal(Object source, HierarchicalStreamWriter writer, MarshallingContext context) {\n    throw new ConversionException(\"Unsupported type due to security reasons.\");\n  }\n}, XStream.PRIORITY_LOW);\n```\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:L/UI:N/S:C/C:H/I:N/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "com.thoughtworks.xstream:xstream"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.4.15"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/x-stream/xstream/security/advisories/GHSA-4cch-wxpw-8p28"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2020-26258"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/x-stream/xstream"
  }, {
    "type" : "WEB",
    "url" : "https://lists.apache.org/thread.html/r97993e3d78e1f5389b7b172ba9f308440830ce5f051ee62714a0aa34%40%3Ccommits.struts.apache.org%3E"
  }, {
    "type" : "WEB",
    "url" : "https://lists.apache.org/thread.html/r97993e3d78e1f5389b7b172ba9f308440830ce5f051ee62714a0aa34@%3Ccommits.struts.apache.org%3E"
  }, {
    "type" : "WEB",
    "url" : "https://lists.debian.org/debian-lts-announce/2020/12/msg00042.html"
  }, {
    "type" : "WEB",
    "url" : "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/22KVR6B5IZP3BGQ3HPWIO2FWWCKT3DHP"
  }, {
    "type" : "WEB",
    "url" : "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PVPHZA7VW2RRSDCOIPP2W6O5ND254TU7"
  }, {
    "type" : "WEB",
    "url" : "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QGXIU3YDPG6OGTDHMBLAFN7BPBERXREB"
  }, {
    "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-20210409-0005"
  }, {
    "type" : "WEB",
    "url" : "https://www.debian.org/security/2021/dsa-4828"
  }, {
    "type" : "WEB",
    "url" : "https://x-stream.github.io/CVE-2020-26258.html"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-918" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2020-12-21T16:21:34Z",
    "nvd_published_at" : "2020-12-16T01:15:00Z"
  }
}

CVSS V3

6.3 MODERATE

Attack Vector Network (AV:N)

Attack Complexity High (AC:H)

Privileges Required Low (PR:L)

User Interaction None (UI:N)

Scope Changed (S:C)

Confidentiality High (C:H)

Integrity None (I:N)

Availability None (A:N)

Vector String

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N

Advisory Metadata

Source ID: GHSA-4cch-wxpw-8p28
Schema Version: 1.4.0
Published: 2020-12-21 16:28
Last Modified: 2025-01-15 21:31
Database Record File: advisories/github-reviewed/2020/12/GHSA-4cch-wxpw-8p28/GHSA-4cch-wxpw-8p28.json