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                             CERT-Renater

                 Note d'Information No. 2021/VULN522
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DATE                : 07/10/2021

HARDWARE PLATFORM(S): /

OPERATING SYSTEM(S): Systems running Jenkins (core) versions prior to
                           weekly 2.315, LTS 2.303.2,
                     Git Plugin versions prior to 4.8.3 .

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https://www.jenkins.io/security/advisory/2021-10-06/
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 Jenkins Security Advisory 2021-10-06

This advisory announces vulnerabilities in the following Jenkins
deliverables:

    Jenkins (core)
    Git Plugin


Descriptions

Improper handling of equivalent directory names on Windows
SECURITY-2424 / CVE-2021-21682

Jenkins stores jobs and other entities on disk using their name shown on
the UI as file and folder names.

On Windows, when specifying a file or folder with a trailing dot
character (example.), the file or folder will be treated as if that
character was not present (example). As both are legal names for jobs
and other entities in Jenkins 2.314 and earlier, LTS 2.303.1 and
earlier, this could allow users with the appropriate permissions to
change or replace configurations of jobs and other entities.

Jenkins 2.315, LTS 2.303.2 does not allow names of jobs and other
entities to end with a dot character.


Jenkins core bundles vulnerable version of the commons-httpclient library
SECURITY-2475 / CVE-2014-3577

Jenkins 2.314 and earlier, LTS 2.303.1 and earlier bundles a version of
the commons-httpclient library with the vulnerability CVE-2014-3577 that
incorrectly verified SSL/TLS certificates, making it susceptible to
man-in-the-middle attacks.

This library is widely used as a transitive dependency in Jenkins
plugins.

The fix for CVE-2014-3577 was backported to the version of
commons-httpclient that is bundled in Jenkins 2.315, LTS 2.303.2 and
made available to plugins.


Path traversal vulnerability on Windows
SECURITY-2481 / CVE-2021-21683

The file browser for workspaces, archived artifacts, and userContent/ in
Jenkins 2.314 and earlier, LTS 2.303.1 and earlier may interpret some
paths to files as absolute on Windows.

This results in a path traversal vulnerability allowing attackers with
Overall/Read permission (Windows controller) or Job/Workspace permission
(Windows agents) to obtain the contents of arbitrary files.

The file browser in Jenkins 2.315, LTS 2.303.2 refuses to serve files
that would be considered absolute paths.


Stored XSS vulnerability in Git Plugin
SECURITY-2499 / CVE-2021-21684

Git Plugin 4.8.2 and earlier does not escape the Git SHA-1 checksum
parameters provided to commit notifications when displaying them in a
build cause.

This results in a stored cross-site scripting (XSS) vulnerability
exploitable by attackers able to submit crafted commit notifications to
the /git/notifyCommit endpoint.

Git Plugin 4.8.3 rejects Git SHA-1 checksum parameters that do not match
the expected format. Existing values are sanitized when displayed on the
UI.

Note
	This vulnerability is only exploitable in Jenkins 2.314 and
earlier, LTS 2.303.1 and earlier. See the LTS upgrade guide.


Severity

    SECURITY-2424: Medium
    SECURITY-2475: Medium
    SECURITY-2481: Medium
    SECURITY-2499: High


Affected Versions

    Jenkins weekly up to and including 2.314
    Jenkins LTS up to and including 2.303.1
    Git Plugin up to and including 4.8.2

Fix

    Jenkins weekly should be updated to version 2.315
    Jenkins LTS should be updated to version 2.303.2
    Git Plugin should be updated to version 4.8.3

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:

    Daniel Beck, CloudBees, Inc. for SECURITY-2499
    Mümin Köykıran for SECURITY-2481
    Wadeck Follonier, CloudBees, Inc., Daniel Beck, CloudBees, Inc., and
James Nord, CloudBees, Inc. for SECURITY-2424


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+ CERT-RENATER       |    tel : 01-53-94-20-44          +
+ 23/25 Rue Daviel   |    fax : 01-53-94-20-41          +
+ 75013 Paris        |    email:cert@support.renater.fr +
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