Authentication bypass in Juniper ScreenOS - CVE-2015-7755
Published: February 1, 2017 / Updated: October 2, 2025
Vulnerability identifier: #VU5587
CSH Severity: Critical
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:A/U:Red
CVE-ID: CVE-2015-7755
CWE-ID: CWE-287
Exploitation vector: Remote access
Exploit availability:
The vulnerability is being exploited in the wild
Vendor: Juniper Networks, Inc.
Affected software:
Juniper ScreenOS
Juniper ScreenOS
Detailed vulnerability description
The vulnerability allows a remote attacker to bypass authentication on the target system.
The weakness exists due to presence of backdoor in Juniper ScreenOS code. A remote attacker can enter a password "<<< %s(un='%s') = %u" during a SSH or TELNET session and obtain administrative access to the device.
Successful exploitation of the vulnerability results in unauthorized access to the vulnerable system.
Note: the vulnerability was being actively exploited.
The weakness exists due to presence of backdoor in Juniper ScreenOS code. A remote attacker can enter a password "<<< %s(un='%s') = %u" during a SSH or TELNET session and obtain administrative access to the device.
Successful exploitation of the vulnerability results in unauthorized access to the vulnerable system.
Note: the vulnerability was being actively exploited.
How to mitigate CVE-2015-7755
Install update from vendor's website.