CVE-2021-21689: Jenkins core Multiple Vulnerabilities Allow Bypassing Path Vulnerability

CRITICAL
Advisory Identifier: GHSA-j3cq-h6vh-gx7f
CVSS 9.0
CWE-862
Published
Advisory Summary

CVE-2021-21689 is a CRITICAL (CVSS 9.0) multiple vulnerabilities allow bypassing path vulnerability (CWE-862: Missing Authorization) affecting Jenkins core libraries in the Maven ecosystem. The issue involves multiple vulnerabilities allow bypassing path filtering of agent-to-controller access control in jenkins. Remediation is available by upgrading affected packages to version 2.303.3, 2.319.

CVE-2021-21689 at a Glance

CVE Identifier CVE-2021-21689
GHSA Identifier GHSA-j3cq-h6vh-gx7f
Severity CRITICAL
CVSS v3.1 Base Score 9.0
CWE Classification CWE-862: Missing Authorization
Affected Product Jenkins core
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 9.0

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:N/S:C/C:H/I:H/A:H).

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

How to Fix CVE-2021-21689

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

org.jenkins-ci.main:jenkins-core fixed: 2.303.3
<dependency>
    <groupId>org.jenkins-ci.main</groupId>
    <artifactId>jenkins-core</artifactId>
    <version>2.303.3</version>
</dependency>
org.jenkins-ci.main:jenkins-core fixed: 2.319
<dependency>
    <groupId>org.jenkins-ci.main</groupId>
    <artifactId>jenkins-core</artifactId>
    <version>2.319</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=org.jenkins-ci.main

How to Check if You Are Affected

To determine whether your Java application is affected by CVE-2021-21689, inspect your build dependencies using the Maven Dependency Plugin:

mvn dependency:tree -Dincludes=org.jenkins-ci.main

Analyze the terminal output to locate any version of Jenkins core in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 2.303.3), your application is affected.

Note: The mvn dependency:tree -Dincludes=org.jenkins-ci.main 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-862: Missing Authorization, where the product does not perform an authorization check when an actor attempts to access a resource or perform an action. In Jenkins core, 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

The agent-to-controller security subsystem limits which files on the Jenkins controller can be accessed by agent processes. Multiple vulnerabilities in the file path filtering implementation of Jenkins 2.318 and earlier, LTS 2.303.2 and earlier allow agent processes to read and write arbitrary files on the Jenkins controller file system, and obtain some information about Jenkins controller file systems. SECURITY-2485 / CVE-2021-21689: `FilePath#unzip` and `FilePath#untar` were not subject to any access control. We expect that most of these vulnerabilities have been present since [SECURITY-144 was addressed in the 2014-10-30 security advisory](https://www.jenkins.io/security/advisory/2014-10-30/). Jenkins 2.319, LTS 2.303.3 addresses these security vulnerabilities. SECURITY-2485 / CVE-2021-21689: `FilePath#unzip` and `FilePath#untar` are now subject to access control. As some common operations are now newly subject to access control, it is expected that plugins sending commands from agents to the controller may start failing. Additionally, the newly introduced path canonicalization means that instances using a custom builds directory ([Java system property jenkins.model.Jenkins.buildsDir](https://www.jenkins.io/doc/book/managing/system-properties/#jenkins-model-jenkins-buildsdir)) or partitioning `JENKINS_HOME` using symbolic links may fail access control checks. See [the documentation](https://www.jenkins.io/doc/book/security/controller-isolation/agent-to-controller/#file-access-rules) for how to customize the configuration in case of problems. If you are unable to immediately upgrade to Jenkins 2.319, LTS 2.303.3, you can install the [Remoting Security Workaround Plugin](https://www.jenkins.io/redirect/remoting-security-workaround/). It will prevent all agent-to-controller file access using `FilePath` APIs. Because it is more restrictive than Jenkins 2.319, LTS 2.303.3, more plugins are incompatible with it. Make sure to read the plugin documentation before installing it.

CVE-2021-21689 Affected Jenkins core Versions

2 component(s)
Fixed Versions:
2.303.32.319
Product / Package Ecosystem Affected Versions Fixed Version
org.jenkins-ci.main:jenkins-core
Maven
< 2.303.3
2.303.3
org.jenkins-ci.main:jenkins-core
Maven
≥ 2.304
< 2.319
2.319

References

Frequently Asked Questions

What is CVE-2021-21689?
CVE-2021-21689 is a security vulnerability in Jenkins core involving Multiple vulnerabilities allow bypassing path filtering of agent-to-controller access control in Jenkins under CWE-862: Missing Authorization.
Which Jenkins core versions are affected?
Affected versions include releases prior to 2.303.3, 2.319 across affected packages: org.jenkins-ci.main:jenkins-core.
What version fixes CVE-2021-21689?
Upgrading to 2.303.3, 2.319 (or the latest patched release for your respective branch) resolves the vulnerability.
Is jenkins-core affected?
Yes, org.jenkins-ci.main:jenkins-core is affected in releases prior to 2.303.3, 2.319. Upgrade your dependency to 2.303.3, 2.319 or later.
What is the CVSS score of CVE-2021-21689?
CVE-2021-21689 has a CVSS v3.1 base score of 9.0 (CRITICAL) with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H.
What CWE is associated with CVE-2021-21689?
CVE-2021-21689 is classified under CWE-862: Missing Authorization (The product does not perform an authorization check when an actor attempts to access a resource or perform an action.).
How can I check Maven dependencies for CVE-2021-21689?
Run the dependency tree command: 'mvn dependency:tree -Dincludes=org.jenkins-ci.main'. 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
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-j3cq-h6vh-gx7f",
  "modified" : "2022-12-16T20:30:17Z",
  "published" : "2022-05-24T19:19:44Z",
  "aliases" : [ "CVE-2021-21689" ],
  "summary" : "Multiple vulnerabilities allow bypassing path filtering of agent-to-controller access control in Jenkins",
  "details" : "The agent-to-controller security subsystem limits which files on the Jenkins controller can be accessed by agent processes.\n\nMultiple vulnerabilities in the file path filtering implementation of Jenkins 2.318 and earlier, LTS 2.303.2 and earlier allow agent processes to read and write arbitrary files on the Jenkins controller file system, and obtain some information about Jenkins controller file systems.\n\nSECURITY-2485 / CVE-2021-21689: `FilePath#unzip` and `FilePath#untar` were not subject to any access control.\n\nWe expect that most of these vulnerabilities have been present since [SECURITY-144 was addressed in the 2014-10-30 security advisory](https://www.jenkins.io/security/advisory/2014-10-30/).\n\nJenkins 2.319, LTS 2.303.3 addresses these security vulnerabilities.\n\nSECURITY-2485 / CVE-2021-21689: `FilePath#unzip` and `FilePath#untar` are now subject to access control.\n\nAs some common operations are now newly subject to access control, it is expected that plugins sending commands from agents to the controller may start failing. Additionally, the newly introduced path canonicalization means that instances using a custom builds directory ([Java system property jenkins.model.Jenkins.buildsDir](https://www.jenkins.io/doc/book/managing/system-properties/#jenkins-model-jenkins-buildsdir)) or partitioning `JENKINS_HOME` using symbolic links may fail access control checks. See [the documentation](https://www.jenkins.io/doc/book/security/controller-isolation/agent-to-controller/#file-access-rules) for how to customize the configuration in case of problems.\n\nIf you are unable to immediately upgrade to Jenkins 2.319, LTS 2.303.3, you can install the [Remoting Security Workaround Plugin](https://www.jenkins.io/redirect/remoting-security-workaround/). It will prevent all agent-to-controller file access using `FilePath` APIs. Because it is more restrictive than Jenkins 2.319, LTS 2.303.3, more plugins are incompatible with it. Make sure to read the plugin documentation before installing it.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "org.jenkins-ci.main:jenkins-core"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "2.303.3"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "org.jenkins-ci.main:jenkins-core"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "2.304"
      }, {
        "fixed" : "2.319"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 2.318"
    }
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-21689"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/jenkinsci/jenkins/commit/104c751d907919dd53f5090f84d53c671a66457b"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/jenkinsci/jenkins/commit/5a245e42979abe4a26d41727c839521e36cedd74"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/jenkinsci/jenkins/commit/63cde2daadc705edf086f2213b48c8c547f98358"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/jenkinsci/jenkins"
  }, {
    "type" : "WEB",
    "url" : "https://www.jenkins.io/security/advisory/2021-11-04/#SECURITY-2455"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-862" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2022-06-23T06:48:33Z",
    "nvd_published_at" : "2021-11-04T17:15:00Z"
  }
}