CVE-2015-7755: Juniper ScreenOS Improper Authentication Vulnerability

Should you act?

Exploited: patch now if you run it

CISA has confirmed exploitation in the wild. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• Yes, if you run Juniper ScreenOS. CISA added this CVE to its Known Exploited Vulnerabilities catalog on 2025-10-02, which means there is reliable evidence of exploitation in the wild. US federal agencies must remediate by 2025-10-23; treat that as the outer limit, not the target.
• EPSS 61.1%, percentile 99: FIRST’s model estimates a 61.1% chance of exploitation activity in the next 30 days, higher than 99% of all scored CVEs (very high). EPSS is a probability, not a verdict.
• Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.

What it is

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, 6.3.0r16 before 6.3.0r16b, 6.3.0r17 before 6.3.0r17b, 6.3.0r18 before 6.3.0r18b, 6.3.0r19 before 6.3.0r19b, and 6.3.0r20 before 6.3.0r21 allows remote attackers to obtain administrative access by entering an unspecified password during a (1) SSH or (2) TELNET session.

CISA’s summary

Juniper ScreenOS contains an improper authentication vulnerability that could allow unauthorized remote administrative access to the device.

Weakness type: CWE-287.

Product: Juniper ScreenOS · Assigned by: mitre · Published: 2015-12-19

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Privileges required: none (no login)
• User interaction: none
• Scope: unchanged

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: added 2025-10-02; federal due date 2025-10-23. Known ransomware use: Unknown.
• CISA required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
• CISA SSVC assessment: exploitation active, automatable yes, technical impact total.
• FIRST EPSS (model of 2026-10-21): 61.14% probability of exploitation activity in the next 30 days; percentile 99.

Timeline

• 2015-12-19 — CVE record published by mitre
• 2025-10-02 — Added to CISA’s Known Exploited Vulnerabilities catalog
• 2025-10-21 — CVE record last updated
• 2025-10-23 — CISA remediation deadline for US federal agencies

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vendor and project advisories, patches

1. Listed in CISA KEV notes (supportportal.juniper.net) supportportal.juniper.net

Vulnerability records

1. CVE.org record CVE-2015-7755 cve.org
2. NVD entry CVE-2015-7755 nvd.nist.gov

Government

1. CISA Known Exploited Vulnerabilities catalog entry cisa.gov

Other references from the CVE record and advisory

1. arstechnica.com arstechnica.com
2. wired.com wired.com
3. 1034489 securitytracker.com
4. VU#640184 kb.cert.org
5. forums.juniper.net forums.juniper.net
6. github.com github.com
7. kb.juniper.net kb.juniper.net
8. twitter.com twitter.com
9. adamcaudill.com adamcaudill.com
10. forbes.com forbes.com
11. 79626 securityfocus.com

All exploited Juniper vulnerabilities · Today’s Security Digest