CVE-2015-7755KEV · OVERDUE

Juniper ScreenOS Improper Authentication Vulnerability

Critical · published December 19, 2015

Patch now

Confirmed exploited, and the score agrees

CVSS calls it critical at 9.8. It is confirmed in active exploitation. It sits in the 99.2th percentile for exploit probability.

365
days past CISA
deadline
CVSS v3.1
9.8
EPSS
61%
Percentile
99.2
In the wild
Confirmed
What it is

🚨 Just type in the right password and voilà! Attackers can get full administrative access to Juniper ScreenOS devices, and it’s mind-blowingly simple! 🔥 Think of it like an online store that lets anyone check out if they just guess a valid discount code — no verification required. With the right string of characters, a bad actor can walk out with the admin's toolkit. This vulnerability allows remote attackers to take complete control of the device, leading to potentially catastrophic consequences — they could manipulate configurations, intercept traffic, and even bring your network to its knees! This is absolutely devastating for any organization relying on Juniper ScreenOS for security.

Put simply

Think of it like an online store that lets anyone check out if they just guess a valid discount code — no verification required. With the right string of characters, a bad actor can walk out with the admin's toolkit. In versions 6.2.0r15 through 6.2.0r18 and 6.3.0r12 to 6.3.0r20, an unauthorized password entry during an SSH or TELNET session grants attackers administrative access, bypassing security protocols entirely.

What to do

This vulnerability allows remote attackers to take complete control of the device, leading to potentially catastrophic consequences — they could manipulate configurations, intercept traffic, and even bring your network to its knees! This is absolutely devastating for any organization relying on Juniper ScreenOS for security. Immediately upgrade to Juniper ScreenOS 6.3.0r21 or later to patch this critical vulnerability. Also, review your firewall configurations and user access controls to tighten security further. Don't leave any stones unturned! You've got this! Follow the steps, secure your network, and take your security hero status to the next level! 🛡️

The record
Technical detail
CVSS v3.1
9.8 · CRITICAL
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS v4.0
Not supplied
EPSS
0.61139 · 99.2th percentile
Published
2015-12-19T11:00Z
KEV added
2025-10-02 · due 2025-10-23
EPSS history
Timeline
  • 02 OCT 00:00Z
    Added to CISA KEV — remediate by Oct 23
    kev
  • 19 DEC 11:00Z
    Juniper ScreenOS 6.2.0r15 through 6.2.0r18, 6.3.0r12 before 6.3.0r12b, 6.3.0r13 before 6.3.0r13b, 6.3.0r14 before 6.3.0r14b, 6.3.0r15 before 6.3.0r15b…
    cvelistv5