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AUSCERT External Security Bulletin Redistribution
Jenkins Security Updates
16 February 2018
AusCERT Security Bulletin Summary
Operating System: UNIX variants (UNIX, Linux, OSX)
Impact/Access: Access Privileged Data -- Existing Account
Provide Misleading Information -- Existing Account
CVE Names: CVE-2018-6356
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Jenkins Security Advisory 2018-02-14
This advisory announces vulnerabilities in the following Jenkins deliverables:
Improperly secured form validation for proxy configuration allowed Server-Side
SECURITY-506 / CVE pending
The form validation for the proxy configuration form did not check the permission
of the user accessing it, allowing anyone with Overall/Read access to Jenkins to
cause Jenkins to send a GET request to a specified URL, optionally with a specified
If that request's HTTP response code indicates success, the form validation is
returning a generic success message, otherwise the HTTP status code is returned.
It was not possible to reuse an existing proxy configuration to send those
requests; that configuration had to be provided by the attacker.
The form validation now properly requires the Overall/Administer permission.
Path traversal vulnerability allows access to files outside plugin resources
SECURITY-705 / CVE-2018-6356
Jenkins did not properly prevent specifying relative paths that escape a base
directory for URLs accessing plugin resource files. This allowed users with
Overall/Read permission to download files from the Jenkins master they should
not have access to.
On Windows, any file accessible to the Jenkins master process could be downloaded.
On other operating systems, any file within the Jenkins home directory accessible
to the Jenkins master process could be downloaded.
Jenkins now prevents specifying paths containing .. and other character sequences
that could be used to access files outside the plugins resource directory.
Improper input validation allows unintended access to plugin resource files on
case-insensitive file systems
SECURITY-717 / CVE pending
Jenkins did not take into account case-insensitive file systems when preventing
access to plugin resource files that should not be accessible. This allowed users
with Overall/Read permission to download plugin resource files in META-INF and
WEB-INF directories, such as the plugins' JAR files, which could contain
This was caused by an incomplete fix to SECURITY-155.
Jenkins weekly up to and including 2.106
Jenkins LTS up to and including 2.89.3
Jenkins weekly should be updated to version 2.107
Jenkins LTS should be updated to version 2.89.4
These versions include fixes to the vulnerabilities described above. All prior
versions are considered to be affected by these vulnerabilities unless
The Jenkins project would like to thank the reporters for discovering and
reporting these vulnerabilities:
Daniel Beck, CloudBees, Inc. for SECURITY-506, SECURITY-717
Kapil Kulkarni for SECURITY-705
Announcement blog post
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