CVE-2015-7755
Published: 19 December 2015
Summary
CVE-2015-7755 is a critical-severity Improper Authentication (CWE-287) vulnerability in Juniper Screenos. Its CVSS base score is 9.8 (Critical).
Operationally, ranked in the top 0.6% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog; a public proof-of-concept is referenced.
The strongest mitigations our analysis identified are NIST 800-53 AC-3 (Access Enforcement) and IA-2 (Identification and Authentication (Organizational Users)).
Deeper analysis
Juniper ScreenOS versions 6.2.0r15 through 6.2.0r18 and multiple 6.3.0 releases up to but not including specific patched builds such as 6.3.0r12b, 6.3.0r13b, and 6.3.0r21 contain an authentication bypass vulnerability. The flaw, assigned CVE-2015-7755 and CWE-287, allows remote attackers to obtain administrative access simply by supplying an unspecified password during SSH or TELNET sessions and carries a CVSS 3.1 score of 9.8.
Any remote attacker with network access to the management interfaces can exploit the issue without authentication to achieve full administrative control of the affected firewall or VPN device. This grants the ability to modify configuration, access sensitive data, or disrupt operations.
Public references including the Juniper advisory JSA10713, CERT VU#640184, and contemporaneous reporting from Ars Technica and Forbes indicate that vendors and researchers published mitigation guidance shortly after disclosure in December 2015.
The same reporting links the vulnerability to broader concerns about unauthorized code present in ScreenOS images, though no confirmed widespread exploitation campaigns are detailed in the provided references.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2015-7655
Vulnerability details
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…
more
by entering an unspecified password during a (1) SSH or (2) TELNET session.
- CWE(s)
- KEV Date Added
- 02 October 2025
Related Threats
No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Directly enforces authentication requirements before granting administrative sessions, blocking the password-bypass that allows unauthenticated SSH/TELNET access.
Mandates identification and authentication of users prior to system access, directly countering the CWE-287 bypass that grants admin rights without valid credentials.
Requires secure authentication and session controls for all remote (SSH/TELNET) management connections, limiting exposure of the affected interfaces.