CVE-2015-7755:

CVE-2015-7755: Juniper ScreenOS allows remote attackers to obtain administrative access by entering an unspecified password during SSH or TELNET sessions in multiple affected releases (e.g., 6.2.0r15–r18 and various 6.3.0 revisions up to 6.3.0r20).

Score
A numerical rating that indicates how dangerous this vulnerability is.

9.8Critical

Published Date:Dec 19, 2015
CISA KEV Date:Oct 2, 2025
Industries Affected:20

Armis Early Warning:

3575 Days

Threat Predictions

EPSS Score:85.6
EPSS Percentile:99%

Exploitability

Score:3.9
Attack Vector:NETWORK
Attack Complexity:LOW
Privileges Required:NONE
User Interaction:NONE
Scope:UNCHANGED

Impact

Score:5.9
Confidentiality Impact:HIGH
Integrity Impact:HIGH
Availability Impact:HIGH

Description Preview

Overview

The CVE describes an authentication bypass vulnerability in Juniper ScreenOS that allows remote attackers to obtain administrative access by supplying an unspecified password during SSH or TELNET sessions. A broad set of older ScreenOS releases are affected, making management interfaces and administrative consoles susceptible to unilateral takeover if exposed to untrusted networks. This issue underscored the risk of unauthorized access to network security devices and prompted immediate vendor advisories and remediation efforts.

Remediation

Upgrade to a fixed ScreenOS release. Juniper provided patches; upgrade to 6.3.0r21 or later (or the vendor’s latest recommended version at the time) to mitigate the vulnerability. Plan the upgrade during a maintenance window, test in a lab environment first, and verify the fix in production.
If immediate upgrade is not possible, restrict management access. Disable or tightly control SSH and TELNET access to management interfaces from untrusted networks. Use VPN or jump hosts and apply strict ACLs to limit who can reach the devices.
Enforce strong authentication and monitor. Ensure administrative accounts use robust, unique passwords, enable multi-factor authentication where available, and monitor logs for unusual login attempts or successful administrative sessions.
Validate post-remediation. After upgrading or applying mitigations, verify that remote admin access requires proper authentication and that devices no longer allow bypass via SSH/TELNET. Review configuration backups and perform a follow-up security assessment.
Consider ongoing hardening. Regularly apply vendor security advisories, keep firmware up to date, and implement network segmentation to minimize exposure of management interfaces.