# CVE-2015-7755: Juniper ScreenOS improper authentication in SSH and Telnet

Source: https://junglewise.ai/threats/cve-2015-7755-juniper-screenos-improper-authentication-in-ssh-and-telnet  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2025-10-02. Updated: 2026-05-15  
License: CC BY 4.0 with a link back

CVE-2015-7755 · Severity: critical · CVSS 9.8 · Exploited in the wild · Published 2025-10-02

Juniper ScreenOS, the operating system for NetScreen firewalls, contains a critical vulnerability that allows unauthorized individuals to gain full administrative control over the device. By using a specific hardcoded password, an attacker can bypass normal security checks to log in remotely via SSH or Telnet. This could lead to complete compromise of the network security infrastructure, allowing attackers to monitor traffic, change security rules, or disable the firewall entirely.

Vendors: [Juniper](https://junglewise.ai/threats/vendors/juniper).

## Quick answers

**Is CVE-2015-7755 exploited in the wild?** Yes. CVE-2015-7755 is known to be exploited in the wild, first recorded on 2 October 2025. Treat it as urgent.

**How severe is CVE-2015-7755?** Critical severity, with a CVSS score of 9.8, published 2 October 2025.

**Which products and versions are affected?** Juniper Networks ScreenOS 6.2.0r15 through 6.2.0r18, 6.3.0r12 through 6.3.0r20 (specific maintenance releases).

**Is there a fix for CVE-2015-7755?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2015-7755 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2015-7755?** Check whether you run Juniper ScreenOS. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

An improper authentication vulnerability (CWE-287) exists in Juniper ScreenOS due to the presence of a hardcoded administrative password. Remote attackers can exploit this by initiating an SSH or Telnet session and entering the specific unauthorized password to gain full administrative privileges. The vulnerability affects ScreenOS versions 6.2.0r15 through 6.2.0r18 and 6.3.0r12 through 6.3.0r20. This flaw has been observed being exploited in the wild and allows for complete compromise of the device's confidentiality, integrity, and availability without requiring any prior authentication or user interaction. Juniper has released patched versions (e.g., 6.3.0r12b, 6.3.0r21) to address this issue.

## Affected products

- Juniper Networks ScreenOS 6.2.0r15 through 6.2.0r18, 6.3.0r12 through 6.3.0r20 (specific maintenance releases)

## Timeline

- 2015-12-17: disclosed: Initial public disclosure of unauthorized code in ScreenOS
- 2025-10-02: kev added: Added to CISA Known Exploited Vulnerabilities catalog