This issue can affect SRX Branch Series devices upgraded using the 'partition' option.

Using the 'request system software' command with the 'partition' option on an SRX Branch Series device upgrading to Junos OS versions 12.1X46-D35, 12.1X46-D40, 12.1X46-D45 can leave the system in a state where root CLI login is allowed without a password due to the system reverting to a "safe mode" authentication. Additionally, valid authentication credentials fail to work for non-root logins due to the same issue.  Only root with no password will work.

A second, related issue was discovered where using the 'request system software' command along with the 'partition' and 'validate' options causes the current configuration to not be validated against the upgraded Junos version as part of the upgrade process.  This could leave the system in a state where root CLI login is allowed without a password post-upgrade when the configuration contains unsupported syntax.  This issue affects Junos OS versions prior to 12.1X46-D65, 12.3X48-D50, and 15.1X49-D80.

No other platform or version of Junos OS is affected by this vulnerability, and no other Juniper Networks products or platforms are affected by this issue.

Juniper SIRT is not aware of any malicious exploitation of this vulnerability.

This issue has been assigned CVE-2016-1278.
 

The following software releases have been updated to resolve these specific upgrade issues: Junos OS 12.1X46-D65, 12.3X48-D50, and 15.1X49-D80, and all subsequent releases.

This issue is being tracked as PRs 1118748, 1153914, and 1223443, which are visible on the Customer Support website.

KB16765 - "In which releases are vulnerabilities fixed?" describes which release vulnerabilities are fixed as per our End of Engineering and End of Life support policies.
 

• Avoid using the 'partition' option when upgrading an SRX Series device to Junos OS 12.1X46-D35, 12.1X46-D40, or 12.1X46-D45.
• Manually validate the current configuration prior to upgrading using the 'partition' and 'validate' options to releases prior to 12.1X46-D65, 12.3X48-D50, and 15.1X49-D80.

Note that the symptoms are immediately obvious after an affected upgrade and may be remediated by rebooting the device post-upgrade.
 

How to obtain fixed software:

Security vulnerabilities in Junos are fixed in the next available Maintenance Release of each supported Junos version. In some cases, a Maintenance Release is not planned to be available in an appropriate time-frame. For these cases, Service Releases are made available in order to be more timely. Security Advisory and Security Notices will indicate which Maintenance and Service Releases contain fixes for the issues described. Upon request to JTAC, customers will be provided download instructions for a Service Release. Although Juniper does not provide formal Release Note documentation for a Service Release, a list of "PRs fixed" can be provided on request.
 

Modification History:

2016-07-13: Initial publication
2016-08-17: Clarified that upgrading from an affected release to a non-affected release will not encounter this issue.
2017-01-09: Updated fixed release from 12.1X46-D50 to 12.1X46-D65 which contains a more complete solution.
2017-01-17: Previous update conflated two similar, but distinct issues.  Reverted back to previous version of JSA.
2017-04-11: Added reference to related issue (PR 1223443) resulting in a similar unauthenticated root CLI situation after upgrading.
 

7.8 (CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H)

Information for how Juniper Networks uses CVSS can be found at KB 16446 "Common Vulnerability Scoring System (CVSS) and Juniper's Security Advisories."