CVE-2020-13933 Nexus Repository Manger 2 & 3 - Shiro Authentication Bypass

Sonatype Nexus Repository Manager 2 & 3 Security Advisory

Date:  October 15th, 2020

Affected Versions:  

  • Nexus Repository Manager 2 versions up to and including 2.14.18
  • Nexus Repository Manager 3 versions up to and including 3.26.1

Fixed in Version:

  • Nexus Repository Manager 2 versions 2.14.19 and later
  • Nexus Repository Manager 3 versions 3.27.0 and later

Risk:  High - 7.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N)

Summary:

CVE-2020-13933 has been discovered in apache-shiro affecting Nexus Repository Manager 2 and 3.

An unauthenticated user can submit a specially crafted HTTP request that may cause an authentication bypass.  We have fixed the issue by upgrading to the latest release of Apache Shiro. This advisory provides the pertinent information needed to properly address this vulnerability, along with the details on how to reach us if you have any further questions or concerns.

We are highly recommending all instances of Nexus Repository Manager 3 be upgraded to 3.27.0 or later and all instances of Nexus Repository Manager 2 be upgraded to 2.14.19 or later. The latest versions can be downloaded from:

Nexus Repository Manager 2 Download

Nexus Repository Manager 3 Download

For detailed information on upgrading, please see:

Nexus Repository Manager 2 Upgrade and Compatibility Notes 

Upgrading Nexus Repository Manager 3.1.0 and Newer

 

Support:

If you run into any problems or have any questions/concerns, please contact us by filing a ticket at https://support.sonatype.com.

 

Frequently Asked Questions:

Q:  What is the risk associated with this vulnerability?

A:  An attacker can craft certain requests that may bypass authentication.  

 

Q: What preconditions must be met in order to be vulnerable?

A: An attacker must have network access to the Nexus Repository Manager instance in order to submit the malicious request.  Therefore, internet-accessible instances imply available access by a very large audience versus the more limited audience associated with non-internet accessible instances.

 

Q: Are there implications associated with this advisory itself?

A: Disclosure unfortunately means bad actors may try to take advantage.  While we have initially limited the information to the minimum details necessary for users to affect an appropriate fix, this merely slows down a would-be attacker.  As such, we are advising all organizations utilizing Nexus Repository Manager to immediately assess their individual impact and take appropriate action in response.

 

Q:  Where can I obtain more information associated with the vulnerability?

A:  For more information, please see the CVE-2020-13933 as well as Apache Shiro Security Reports.  They contain information as well as links to further discussions and code changes.  

 

Q:  Why is Sonatype making this information available?

A:  This is part of a responsible disclosure process.  Given Nexus Repository Manager is an open-source project with over 150,000 active server installations, notifying the user base will invariably lead to broad dissemination.  We are taking a concerted and proactive approach in our outreach activities and an effort to achieve the most rapid remediation possible.

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