CVE-2021-21615: Jenkins core Time-of-check Time-of-use (TOCTOU) Race Condition Vulnerability
MODERATECVE-2021-21615 is a MODERATE (CVSS 5.3) time-of-check time-of-use (toctou) race condition vulnerability (CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition) affecting Jenkins core libraries in the Maven ecosystem. The issue involves time-of-check time-of-use (toctou) race condition in jenkins. Remediation is available by upgrading affected packages to version 2.263.3, 2.276.
CVE-2021-21615 at a Glance
Security Impact
CVSS: 5.3
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:U/C:H/I:N/A:N).
How to Fix CVE-2021-21615
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.
<dependency>
<groupId>org.jenkins-ci.main</groupId>
<artifactId>jenkins-core</artifactId>
<version>2.263.3</version>
</dependency><dependency>
<groupId>org.jenkins-ci.main</groupId>
<artifactId>jenkins-core</artifactId>
<version>2.276</version>
</dependency>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.mainHow to Check if You Are Affected
To determine whether your Java application is affected by CVE-2021-21615, inspect your build dependencies using the Maven Dependency Plugin:
mvn dependency:tree -Dincludes=org.jenkins-ci.mainAnalyze 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 2.263.3), 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-367: Time-of-check Time-of-use (TOCTOU) Race Condition, where the product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of 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
CVE-2021-21615 Affected Jenkins core Versions
2 component(s)| Product / Package | Ecosystem | Affected Versions | Fixed Version |
|---|---|---|---|
|
org.jenkins-ci.main:jenkins-core
|
Maven |
< 2.263.3
|
2.263.3
|
|
org.jenkins-ci.main:jenkins-core
|
Maven |
≥ 2.264
< 2.276
|
2.276
|
References
Frequently Asked Questions
What is CVE-2021-21615?
Which Jenkins core versions are affected?
What version fixes CVE-2021-21615?
Is jenkins-core affected?
What is the CVSS score of CVE-2021-21615?
What CWE is associated with CVE-2021-21615?
How can I check Maven dependencies for CVE-2021-21615?
Machine-readable OSV JSON
OSV v1.5 Schema
{
"schema_version" : "1.4.0",
"id" : "GHSA-qxp6-27gw-99cj",
"modified" : "2022-12-13T15:58:50Z",
"published" : "2022-05-24T17:40:19Z",
"aliases" : [ "CVE-2021-21615" ],
"summary" : "Time-of-check Time-of-use (TOCTOU) Race Condition in Jenkins",
"details" : "Due to a time-of-check to time-of-use (TOCTOU) race condition, the file browser for workspaces, archived artifacts, and `$JENKINS_HOME/userContent/` follows symbolic links to locations outside the directory being browsed in Jenkins 2.275 and LTS 2.263.2.\n\nThis allows attackers with Job/Workspace permission and the ability to control workspace contents, e.g., with Job/Configure permission or the ability to change SCM contents, to create symbolic links that allow them to access files outside workspaces using the workspace browser.\n\nThis issue is caused by an incorrectly applied fix for SECURITY-1452 / CVE-2021-21602 in the [2021-01-13 security advisory](https://www.jenkins.io/security/advisory/2021-01-13/#SECURITY-1452).\n\nJenkins 2.276, LTS 2.263.3 no longer differentiates the check and the use of symlinks in workspace browsers.",
"severity" : [ {
"type" : "CVSS_V3",
"score" : "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N"
} ],
"affected" : [ {
"package" : {
"ecosystem" : "Maven",
"name" : "org.jenkins-ci.main:jenkins-core"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "0"
}, {
"fixed" : "2.263.3"
} ]
} ],
"database_specific" : {
"last_known_affected_version_range" : "<= 2.263.2"
}
}, {
"package" : {
"ecosystem" : "Maven",
"name" : "org.jenkins-ci.main:jenkins-core"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "2.264"
}, {
"fixed" : "2.276"
} ]
} ],
"database_specific" : {
"last_known_affected_version_range" : "<= 2.275"
}
} ],
"references" : [ {
"type" : "ADVISORY",
"url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-21615"
}, {
"type" : "WEB",
"url" : "https://www.jenkins.io/security/advisory/2021-01-26/#SECURITY-2197"
}, {
"type" : "WEB",
"url" : "http://www.openwall.com/lists/oss-security/2021/01/26/2"
} ],
"database_specific" : {
"cwe_ids" : [ "CWE-367" ],
"severity" : "MODERATE",
"github_reviewed" : true,
"github_reviewed_at" : "2022-06-23T06:50:38Z",
"nvd_published_at" : "2021-01-26T18:16:00Z"
}
}