CVE-2021-21678: Saml Jenkins SAML Plugin Allows Bypassing Vulnerability

HIGH
Advisory Identifier: GHSA-r5w3-pfq8-3r82
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CVSS 8.8
CWE-693 CWE-352
Published
Advisory Summary

CVE-2021-21678 is a HIGH (CVSS 8.8) jenkins saml plugin allows bypassing vulnerability (CWE-693: Protection Mechanism Failure) affecting Saml libraries in the Maven ecosystem. The issue involves jenkins saml plugin allows bypassing csrf protection for any url. Remediation is available by upgrading affected packages to version 2.0.8.

CVE-2021-21678 at a Glance

CVE Identifier CVE-2021-21678
GHSA Identifier GHSA-r5w3-pfq8-3r82
Severity HIGH
CVSS v3.1 Base Score 8.8
CWE Classification CWE-693: Protection Mechanism Failure
Affected Product Saml
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:N/UI:R/S:U/C:H/I:H/A:H).

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

How to Fix CVE-2021-21678

To remediate this vulnerability, upgrade all affected Saml 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:saml fixed: 2.0.8 
<dependency>
    <groupId>org.jenkins-ci.plugins</groupId>
    <artifactId>saml</artifactId>
    <version>2.0.8</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-2021-21678, 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 Saml in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 2.0.8), 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 Saml, 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

An extension point in Jenkins allows selectively disabling cross-site request forgery (CSRF) protection for specific URLs. SAML Plugin implements this extension point for the URL that users are redirected to after login. In Jenkins SAML Plugin 2.0.7 and earlier this implementation is too permissive, allowing attackers to craft URLs that would bypass the CSRF protection of any target URL.\n\nThis vulnerability was originally introduced in Jenkins SAML Plugin 1.1.3. Jenkins SAML Plugin 2.0.8 restricts which URLs it disables cross-site request forgery (CSRF) protection for to the one URL that needs it.

CVE-2021-21678 Affected Saml Versions

1 component(s)
Fixed Versions:
2.0.8
Product / Package Ecosystem Affected Versions Fixed Version
org.jenkins-ci.plugins:saml
maven/org.jenkins-ci.plugins/saml
Maven
< 2.0.8
2.0.8

References

NVD — CVE-2021-21678 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-21678
Security Fix Commit FIX COMMIT
https://github.com/jenkinsci/saml-plugin/commit/e063317ee7e1c64a096e0ac323c7155b786c8b9d
Saml Source Repository REPOSITORY
https://github.com/jenkinsci/saml-plugin
Saml Security Information SECURITY
https://www.jenkins.io/security/advisory/2021-08-31/#SECURITY-2469
Saml Security Information SECURITY
http://www.openwall.com/lists/oss-security/2021/08/31/1

Frequently Asked Questions

What is CVE-2021-21678?
CVE-2021-21678 is a security vulnerability in Saml involving Jenkins SAML Plugin allows bypassing CSRF protection for any URL under CWE-693: Protection Mechanism Failure.
Which Saml versions are affected?
Affected versions include releases prior to 2.0.8 across affected packages: org.jenkins-ci.plugins:saml.
What version fixes CVE-2021-21678?
Upgrading to 2.0.8 (or the latest patched release for your respective branch) resolves the vulnerability.
Is saml affected?
Yes, org.jenkins-ci.plugins:saml is affected in releases prior to 2.0.8. Upgrade your dependency to 2.0.8 or later.
What is the CVSS score of CVE-2021-21678?
CVE-2021-21678 has a CVSS v3.1 base score of 8.8 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.
What CWE is associated with CVE-2021-21678?
CVE-2021-21678 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-2021-21678?
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-r5w3-pfq8-3r82",
  "modified" : "2023-10-27T16:01:54Z",
  "published" : "2022-05-24T19:12:37Z",
  "aliases" : [ "CVE-2021-21678" ],
  "summary" : "Jenkins SAML Plugin allows bypassing CSRF protection for any URL",
  "details" : "An extension point in Jenkins allows selectively disabling cross-site request forgery (CSRF) protection for specific URLs. SAML Plugin implements this extension point for the URL that users are redirected to after login.\n\nIn Jenkins SAML Plugin 2.0.7 and earlier this implementation is too permissive, allowing attackers to craft URLs that would bypass the CSRF protection of any target URL.\\n\\nThis vulnerability was originally introduced in Jenkins SAML Plugin 1.1.3.\n\nJenkins SAML Plugin 2.0.8 restricts which URLs it disables cross-site request forgery (CSRF) protection for to the one URL that needs it.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "org.jenkins-ci.plugins:saml"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "2.0.8"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 2.0.7"
    }
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-21678"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/jenkinsci/saml-plugin/commit/e063317ee7e1c64a096e0ac323c7155b786c8b9d"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/jenkinsci/saml-plugin"
  }, {
    "type" : "WEB",
    "url" : "https://www.jenkins.io/security/advisory/2021-08-31/#SECURITY-2469"
  }, {
    "type" : "WEB",
    "url" : "http://www.openwall.com/lists/oss-security/2021/08/31/1"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-352", "CWE-693" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2022-12-15T16:35:03Z",
    "nvd_published_at" : "2021-08-31T14:15:00Z"
  }
}