CVE-2021-21670: Jenkins core Improper Permission Checks Allow Canceling Vulnerability

MODERATE
Advisory Identifier: GHSA-q4wp-8c99-69pw
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CVSS 4.3
CWE-863
Published
Advisory Summary

CVE-2021-21670 is a MODERATE (CVSS 4.3) improper permission checks allow canceling vulnerability (CWE-863: Incorrect Authorization) affecting Jenkins core libraries in the Maven ecosystem. The issue involves improper permission checks allow canceling queue items and aborting builds in jenkins. Remediation is available by upgrading affected packages to version 2.289.2, 2.300.

CVE-2021-21670 at a Glance

CVE Identifier CVE-2021-21670
GHSA Identifier GHSA-q4wp-8c99-69pw
Severity MODERATE
CVSS v3.1 Base Score 4.3
CWE Classification CWE-863: Incorrect Authorization
Affected Product Jenkins core
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 4.3

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

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required Low (PR:L)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality None (C:N)
Integrity Low (I:L)
Availability None (A:N)

How to Fix CVE-2021-21670

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: 2.289.2 
<dependency>
    <groupId>org.jenkins-ci.main</groupId>
    <artifactId>jenkins-core</artifactId>
    <version>2.289.2</version>
</dependency>
org.jenkins-ci.main:jenkins-core fixed: 2.300 
<dependency>
    <groupId>org.jenkins-ci.main</groupId>
    <artifactId>jenkins-core</artifactId>
    <version>2.300</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-2021-21670, 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 2.289.2), 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-863: Incorrect Authorization, where the product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check. 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

Jenkins 2.299 and earlier, LTS 2.289.1 and earlier allows users to cancel queue items and abort builds of jobs for which they have Item/Cancel permission even when they do not have Item/Read permission. Jenkins 2.300, LTS 2.289.2 requires that users have Item/Read permission for applicable types in addition to Item/Cancel permission. As a workaround on earlier versions of Jenkins, do not grant Item/Cancel permission to users who do not have Item/Read permission.

CVE-2021-21670 Affected Jenkins core Versions

2 component(s)
Fixed Versions:
2.289.22.300
Product / Package Ecosystem Affected Versions Fixed Version
org.jenkins-ci.main:jenkins-core
maven/org.jenkins-ci.main/jenkins-core
Maven
< 2.289.2
2.289.2
org.jenkins-ci.main:jenkins-core
maven/org.jenkins-ci.main/jenkins-core
Maven
≥ 2.292
< 2.300
2.300

References

NVD — CVE-2021-21670 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-21670
Security Fix Commit FIX COMMIT
https://github.com/jenkinsci/jenkins/commit/86b7d7e789586575522650c60d591605facb1d70
Jenkins core Source Repository REPOSITORY
https://github.com/jenkinsci/jenkins
Jenkins core Security Information SECURITY
https://www.jenkins.io/security/advisory/2021-06-30/#SECURITY-2278
Jenkins core Security Information SECURITY
http://www.openwall.com/lists/oss-security/2021/06/30/1

Frequently Asked Questions

What is CVE-2021-21670?
CVE-2021-21670 is a security vulnerability in Jenkins core involving Improper permission checks allow canceling queue items and aborting builds in Jenkins under CWE-863: Incorrect Authorization.
Which Jenkins core versions are affected?
Affected versions include releases prior to 2.289.2, 2.300 across affected packages: org.jenkins-ci.main:jenkins-core.
What version fixes CVE-2021-21670?
Upgrading to 2.289.2, 2.300 (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 2.289.2, 2.300. Upgrade your dependency to 2.289.2, 2.300 or later.
What is the CVSS score of CVE-2021-21670?
CVE-2021-21670 has a CVSS v3.1 base score of 4.3 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N.
What CWE is associated with CVE-2021-21670?
CVE-2021-21670 is classified under CWE-863: Incorrect Authorization (The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check.).
How can I check Maven dependencies for CVE-2021-21670?
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
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-q4wp-8c99-69pw",
  "modified" : "2022-12-16T15:22:17Z",
  "published" : "2022-05-24T19:06:36Z",
  "aliases" : [ "CVE-2021-21670" ],
  "summary" : "Improper permission checks allow canceling queue items and aborting builds in Jenkins",
  "details" : "Jenkins 2.299 and earlier, LTS 2.289.1 and earlier allows users to cancel queue items and abort builds of jobs for which they have Item/Cancel permission even when they do not have Item/Read permission.\n\nJenkins 2.300, LTS 2.289.2 requires that users have Item/Read permission for applicable types in addition to Item/Cancel permission.\n\nAs a workaround on earlier versions of Jenkins, do not grant Item/Cancel permission to users who do not have Item/Read permission.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "org.jenkins-ci.main:jenkins-core"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "2.289.2"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 2.289.1"
    }
  }, {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "org.jenkins-ci.main:jenkins-core"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "2.292"
      }, {
        "fixed" : "2.300"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 2.299"
    }
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-21670"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/jenkinsci/jenkins/commit/86b7d7e789586575522650c60d591605facb1d70"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/jenkinsci/jenkins"
  }, {
    "type" : "WEB",
    "url" : "https://www.jenkins.io/security/advisory/2021-06-30/#SECURITY-2278"
  }, {
    "type" : "WEB",
    "url" : "http://www.openwall.com/lists/oss-security/2021/06/30/1"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-863" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2022-12-16T15:22:17Z",
    "nvd_published_at" : "2021-06-30T17:15:00Z"
  }
}