CVE-2021-21640: Jenkins core View Name Validation Bypass Vulnerability

MODERATE
Advisory Identifier: GHSA-w2hv-rcqr-2h7r
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CVSS 4.3
CWE-240
Published
Advisory Summary

CVE-2021-21640 is a MODERATE (CVSS 4.3) view name validation bypass vulnerability (CWE-240: Improper Handling of Inconsistent Structural Elements) affecting Jenkins core libraries in the Maven ecosystem. The issue involves view name validation bypass in jenkins. Remediation is available by upgrading affected packages to version 2.277.2, 2.287.

CVE-2021-21640 at a Glance

CVE Identifier CVE-2021-21640
GHSA Identifier GHSA-w2hv-rcqr-2h7r
Severity MODERATE
CVSS v3.1 Base Score 4.3
CWE Classification CWE-240: Improper Handling of Inconsistent Structural Elements
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-2021-21640

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: 2.277.2 
<dependency>
    <groupId>org.jenkins-ci.main</groupId>
    <artifactId>jenkins-core</artifactId>
    <version>2.277.2</version>
</dependency>
org.jenkins-ci.main:jenkins-core fixed: 2.287 
<dependency>
    <groupId>org.jenkins-ci.main</groupId>
    <artifactId>jenkins-core</artifactId>
    <version>2.287</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-2021-21640, 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 2.277.2), 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-240: Improper Handling of Inconsistent Structural Elements, where the product does not handle or incorrectly handles when two or more structural elements should be consistent, but are not. 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 2.286 and earlier, LTS 2.277.1 and earlier does not properly check that a newly created view has an allowed name. When a form to create a view is submitted, the name is included twice in the submission. One instance is validated, but the other instance is used to create the value. This allows attackers with View/Create permission to create views with invalid or already-used names. Jenkins 2.287, LTS 2.277.2 uses the same submitted value for validation and view creation.

CVE-2021-21640 Affected Jenkins core Versions

2 component(s)
Fixed Versions:
2.277.22.287
Product / Package Ecosystem Affected Versions Fixed Version
org.jenkins-ci.main:jenkins-core
maven/org.jenkins-ci.main/jenkins-core
Maven
< 2.277.2
2.277.2
org.jenkins-ci.main:jenkins-core
maven/org.jenkins-ci.main/jenkins-core
Maven
≥ 2.278
< 2.287
2.287

References

NVD — CVE-2021-21640 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-21640
Security Fix Commit FIX COMMIT
https://github.com/jenkinsci/jenkins/commit/42e2c74049ddf5e0aca1fe6aadc7b24fdabb5494
Jenkins core Source Repository REPOSITORY
https://github.com/jenkinsci/jenkins
Jenkins core Security Information SECURITY
https://www.jenkins.io/security/advisory/2021-04-07/#SECURITY-1871
Jenkins core Security Information SECURITY
http://www.openwall.com/lists/oss-security/2021/04/07/2

Frequently Asked Questions

What is CVE-2021-21640?
CVE-2021-21640 is a security vulnerability in Jenkins core involving View name validation bypass in Jenkins under CWE-240: Improper Handling of Inconsistent Structural Elements.
Which Jenkins core versions are affected?
Affected versions include releases prior to 2.277.2, 2.287 across affected packages: org.jenkins-ci.main:jenkins-core.
What version fixes CVE-2021-21640?
Upgrading to 2.277.2, 2.287 (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 2.277.2, 2.287. Upgrade your dependency to 2.277.2, 2.287 or later.
What is the CVSS score of CVE-2021-21640?
CVE-2021-21640 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-2021-21640?
CVE-2021-21640 is classified under CWE-240: Improper Handling of Inconsistent Structural Elements (The product does not handle or incorrectly handles when two or more structural elements should be consistent, but are not.).
How can I check Maven dependencies for CVE-2021-21640?
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-w2hv-rcqr-2h7r",
  "modified" : "2022-12-13T16:47:01Z",
  "published" : "2022-05-24T17:46:47Z",
  "aliases" : [ "CVE-2021-21640" ],
  "summary" : "View name validation bypass in Jenkins",
  "details" : "Jenkins 2.286 and earlier, LTS 2.277.1 and earlier does not properly check that a newly created view has an allowed name. When a form to create a view is submitted, the name is included twice in the submission. One instance is validated, but the other instance is used to create the value.\n\nThis allows attackers with View/Create permission to create views with invalid or already-used names.\n\nJenkins 2.287, LTS 2.277.2 uses the same submitted value for validation and view creation.",
  "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" : "2.277.2"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "org.jenkins-ci.main:jenkins-core"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "2.278"
      }, {
        "fixed" : "2.287"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 2.286"
    }
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-21640"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/jenkinsci/jenkins/commit/42e2c74049ddf5e0aca1fe6aadc7b24fdabb5494"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/jenkinsci/jenkins"
  }, {
    "type" : "WEB",
    "url" : "https://www.jenkins.io/security/advisory/2021-04-07/#SECURITY-1871"
  }, {
    "type" : "WEB",
    "url" : "http://www.openwall.com/lists/oss-security/2021/04/07/2"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-240" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2022-06-23T06:49:47Z",
    "nvd_published_at" : "2021-04-07T14:15:00Z"
  }
}