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             AUSCERT External Security Bulletin Redistribution

                   Jenkins Security Advisory 2021-01-26
                              27 January 2021


        AusCERT Security Bulletin Summary

Product:           Jenkins Core
Publisher:         Jenkins
Operating System:  Windows
                   UNIX variants (UNIX, Linux, OSX)
Impact/Access:     Access Confidential Data -- Existing Account
                   Reduced Security         -- Existing Account
Resolution:        Patch/Upgrade
CVE Names:         CVE-2021-21615 CVE-2021-21602 

Reference:         ESB-2021.0191

Original Bulletin: 

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Jenkins Security Advisory 2021-01-26  

This advisory announces vulnerabilities in the following Jenkins deliverables:

  o Jenkins (core)


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.

Note 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.


  o SECURITY-2197: Medium

Affected Versions  

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


  o Jenkins weekly should be updated to version 2.276
  o 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.


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

  o Wadeck Follonier, CloudBees, Inc. and Daniel Beck, CloudBees, Inc. for

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