CVE-2021-21671: Jenkins core Session Fixation Vulnerability Vulnerability
HIGHCVE-2021-21671 is a HIGH (CVSS 7.5) session fixation vulnerability vulnerability (CWE-384: Session Fixation) affecting Jenkins core libraries in the Maven ecosystem. The issue involves session fixation vulnerability in jenkins. Remediation is available by upgrading affected packages to version 2.300, 2.289.2.
CVE-2021-21671 at a Glance
Security Impact
CVSS: 7.5
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:R/S:U/C:H/I:H/A:H).
How to Fix CVE-2021-21671
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>2.300</version>
</dependency><dependency>
<groupId>org.jenkins-ci.main</groupId>
<artifactId>jenkins-core</artifactId>
<version>2.289.2</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-2021-21671, 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 2.300), 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-384: Session Fixation, where authenticating a user, or otherwise establishing a new user session, without invalidating any existing session identifier gives an attacker the opportunity to steal authenticated sessions. 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-2021-21671 Affected Jenkins core Versions
2 component(s)| Product / Package | Ecosystem | Affected Versions | Fixed Version |
|---|---|---|---|
|
org.jenkins-ci.main:jenkins-core
|
Maven |
≥ 2.292
< 2.300
|
2.300
|
|
org.jenkins-ci.main:jenkins-core
|
Maven |
< 2.289.2
|
2.289.2
|
References
Frequently Asked Questions
What is CVE-2021-21671?
Which Jenkins core versions are affected?
What version fixes CVE-2021-21671?
Is jenkins-core affected?
What is the CVSS score of CVE-2021-21671?
What CWE is associated with CVE-2021-21671?
How can I check Maven dependencies for CVE-2021-21671?
Machine-readable OSV JSON
OSV v1.5 Schema
{
"schema_version" : "1.4.0",
"id" : "GHSA-4wr9-2xc6-jmg5",
"modified" : "2023-10-27T15:36:00Z",
"published" : "2022-05-24T19:06:36Z",
"aliases" : [ "CVE-2021-21671" ],
"summary" : "Session fixation vulnerability in Jenkins",
"details" : "Jenkins 2.299 and earlier, LTS 2.289.1 and earlier does not invalidate the previous session on login. This allows attackers to use social engineering techniques to gain administrator access to Jenkins.\n\nThis vulnerability was introduced in Jenkins 2.266 and LTS 2.277.1.\n\nJenkins 2.300, LTS 2.289.2 invalidates the previous session on login.\n\nIn case of problems, administrators can choose a different implementation by setting the [Java system property `hudson.security.SecurityRealm.sessionFixationProtectionMode`](https://www.jenkins.io/doc/book/managing/system-properties/#hudson-security-securityrealm-sessionfixationprotectionmode) to `2`, or disable the fix entirely by setting that system property to `0`.",
"severity" : [ {
"type" : "CVSS_V3",
"score" : "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H"
} ],
"affected" : [ {
"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"
}
}, {
"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"
}
} ],
"references" : [ {
"type" : "ADVISORY",
"url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-21671"
}, {
"type" : "WEB",
"url" : "https://github.com/jenkinsci/jenkins/commit/25a42f3942fd9f8bd768c887c679dbc796b4fcd5"
}, {
"type" : "PACKAGE",
"url" : "https://github.com/jenkinsci/jenkins"
}, {
"type" : "WEB",
"url" : "https://www.jenkins.io/security/advisory/2021-06-30/#SECURITY-2371"
}, {
"type" : "WEB",
"url" : "http://www.openwall.com/lists/oss-security/2021/06/30/1"
} ],
"database_specific" : {
"cwe_ids" : [ "CWE-384" ],
"severity" : "HIGH",
"github_reviewed" : true,
"github_reviewed_at" : "2022-12-16T15:20:37Z",
"nvd_published_at" : "2021-06-30T17:15:00Z"
}
}