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Missing permission check for paths with specific prefix in Jenkins

Moderate severity GitHub Reviewed Published May 24, 2022 to the GitHub Advisory Database • Updated Dec 14, 2023

Package

maven org.jenkins-ci.main:jenkins-core (Maven)

Affected versions

<= 2.263.1
>= 2.264, <= 2.274

Patched versions

2.263.2
2.275

Description

Jenkins includes a static list of URLs that are always accessible even without Overall/Read permission, such as the login form. These URLs are excluded from an otherwise universal permission check.

Jenkins 2.274 and earlier, LTS 2.263.1 and earlier does not correctly compare requested URLs with that list.

This allows attackers without Overall/Read permission to access plugin-provided URLs with any of the following prefixes if no other permissions are required:

  • accessDenied
  • error
  • instance-identity
  • login
  • logout
  • oops
  • securityRealm
  • signup
  • tcpSlaveAgentListener

For example, a plugin contributing the path loginFoo/ would have URLs in that space accessible without the default Overall/Read permission check.

The Jenkins security team is not aware of any affected plugins as of the publication of this advisory.

The comparison of requested URLs with the list of always accessible URLs has been fixed to only allow access to the specific listed URLs in Jenkins 2.275, LTS 2.263.2.

In case this change causes problems, additional paths can be made accessible without Overall/Read permissions: The Java system property jenkins.model.Jenkins.additionalReadablePaths is a comma-separated list of additional path prefixes to allow access to.

References

Published by the National Vulnerability Database Jan 13, 2021
Published to the GitHub Advisory Database May 24, 2022
Reviewed Jun 23, 2022
Last updated Dec 14, 2023

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

EPSS score

0.084%
(37th percentile)

Weaknesses

CVE ID

CVE-2021-21609

GHSA ID

GHSA-4625-q52w-39cx

Source code

Credits

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