CVE-2021-21646: Templating engine Remote Code Execution Vulnerability

HIGH
Advisory Identifier: GHSA-p6qc-37hq-wqr6
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CVSS 8.8
CWE-693
Published
Advisory Summary

CVE-2021-21646 is a HIGH (CVSS 8.8) remote code execution vulnerability (CWE-693: Protection Mechanism Failure) affecting Templating engine libraries in the Maven ecosystem. The issue involves remote code execution vulnerability in jenkins templating engine plugin. Remediation is available by upgrading affected packages to version 2.2.

CVE-2021-21646 at a Glance

CVE Identifier CVE-2021-21646
GHSA Identifier GHSA-p6qc-37hq-wqr6
Severity HIGH
CVSS v3.1 Base Score 8.8
CWE Classification CWE-693: Protection Mechanism Failure
Affected Product Templating engine
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 8.8

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:H/I:H/A:H).

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 High (C:H)
Integrity High (I:H)
Availability High (A:H)

How to Fix CVE-2021-21646

To remediate this vulnerability, upgrade all affected Templating engine 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.plugins:templating-engine fixed: 2.2 
<dependency>
    <groupId>org.jenkins-ci.plugins</groupId>
    <artifactId>templating-engine</artifactId>
    <version>2.2</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.plugins

How to Check if You Are Affected

To determine whether your Java application is affected by CVE-2021-21646, inspect your build dependencies using the Maven Dependency Plugin:

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

Analyze the terminal output to locate any version of Templating engine in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 2.2), your application is affected.

Note: The mvn dependency:tree -Dincludes=org.jenkins-ci.plugins 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-693: Protection Mechanism Failure, where the product does not use or incorrectly uses a protection mechanism that provides sufficient defense against directed attacks against the product. In Templating engine, 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 Templating Engine Plugin 2.1 and earlier does not protect its pipeline configurations using Script Security Plugin. This vulnerability allows attackers with Job/Configure permission to execute arbitrary code in the context of the Jenkins controller JVM. Jenkins Templating Engine Plugin 2.2 integrates with Script Security Plugin to protect its pipeline configurations.

CVE-2021-21646 Affected Templating engine Versions

1 component(s)
Fixed Versions:
2.2
Product / Package Ecosystem Affected Versions Fixed Version
org.jenkins-ci.plugins:templating-engine
maven/org.jenkins-ci.plugins/templating-engine
Maven
< 2.2
2.2

References

NVD — CVE-2021-21646 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-21646
Security Fix Commit FIX COMMIT
https://github.com/jenkinsci/templating-engine-plugin/commit/aed14bed7333329f51330d0a8111e4d94cdee3e6
Templating engine Source Repository REPOSITORY
https://github.com/jenkinsci/templating-engine-plugin
Templating engine Security Information SECURITY
https://www.jenkins.io/security/advisory/2021-04-21/#SECURITY-2311
Templating engine Security Information SECURITY
http://www.openwall.com/lists/oss-security/2021/04/21/2

Frequently Asked Questions

What is CVE-2021-21646?
CVE-2021-21646 is a security vulnerability in Templating engine involving Remote code execution vulnerability in Jenkins Templating Engine Plugin under CWE-693: Protection Mechanism Failure.
Which Templating engine versions are affected?
Affected versions include releases prior to 2.2 across affected packages: org.jenkins-ci.plugins:templating-engine.
What version fixes CVE-2021-21646?
Upgrading to 2.2 (or the latest patched release for your respective branch) resolves the vulnerability.
Is templating-engine affected?
Yes, org.jenkins-ci.plugins:templating-engine is affected in releases prior to 2.2. Upgrade your dependency to 2.2 or later.
What is the CVSS score of CVE-2021-21646?
CVE-2021-21646 has a CVSS v3.1 base score of 8.8 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.
What CWE is associated with CVE-2021-21646?
CVE-2021-21646 is classified under CWE-693: Protection Mechanism Failure (The product does not use or incorrectly uses a protection mechanism that provides sufficient defense against directed attacks against the product.).
How can I check Maven dependencies for CVE-2021-21646?
Run the dependency tree command: 'mvn dependency:tree -Dincludes=org.jenkins-ci.plugins'. 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-p6qc-37hq-wqr6",
  "modified" : "2023-10-27T14:24:29Z",
  "published" : "2022-05-24T17:48:06Z",
  "aliases" : [ "CVE-2021-21646" ],
  "summary" : "Remote code execution vulnerability in Jenkins Templating Engine Plugin",
  "details" : "Jenkins Templating Engine Plugin 2.1 and earlier does not protect its pipeline configurations using Script Security Plugin.\n\nThis vulnerability allows attackers with Job/Configure permission to execute arbitrary code in the context of the Jenkins controller JVM.\n\nJenkins Templating Engine Plugin 2.2 integrates with Script Security Plugin to protect its pipeline configurations.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "org.jenkins-ci.plugins:templating-engine"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "2.2"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 2.1"
    }
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-21646"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/jenkinsci/templating-engine-plugin/commit/aed14bed7333329f51330d0a8111e4d94cdee3e6"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/jenkinsci/templating-engine-plugin"
  }, {
    "type" : "WEB",
    "url" : "https://www.jenkins.io/security/advisory/2021-04-21/#SECURITY-2311"
  }, {
    "type" : "WEB",
    "url" : "http://www.openwall.com/lists/oss-security/2021/04/21/2"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-693" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2022-12-13T19:28:15Z",
    "nvd_published_at" : "2021-04-21T15:15:00Z"
  }
}