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Jenkins Security Advisory 2021-01-26

This advisory announces vulnerabilities in the following Jenkins deliverables:

  • Jenkins (core)

Descriptions

Arbitrary file read vulnerability in workspace browsers

SECURITY-2197 / CVE-2021-21615

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.

This 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.

This issue is caused by an incorrectly applied fix for SECURITY-1452 / CVE-2021-21602 in the 2021-01-13 security advisory.

Jenkins 2.276, LTS 2.263.3 no longer differentiates the check and the use of symlinks in workspace browsers.

Severity

Affected Versions

  • Jenkins weekly up to and including 2.275
  • Jenkins LTS up to and including 2.263.2

Fix

  • Jenkins weekly should be updated to version 2.276
  • Jenkins LTS should be updated to version 2.263.3

These versions include fixes to the vulnerabilities described above. All prior versions are considered to be affected by these vulnerabilities unless otherwise indicated.

Credit

The Jenkins project would like to thank the reporters for discovering and reporting these vulnerabilities:

  • Wadeck Follonier, CloudBees, Inc. and Daniel Beck, CloudBees, Inc. for SECURITY-2197