A Missing Authentication for Critical Function vulnerability in Juniper Networks Junos OS on EX Series allows an unauthenticated, network-based attacker to cause limited impact to the file system integrity.
With a specific request to installAppPackage.php that doesn't require authentication an attacker is able to upload arbitrary files via J-Web, leading to a loss of
integrity
for a certain
part of the file system, which may allow chaining to other vulnerabilities.
This issue affects Juniper Networks Junos OS on EX Series:
prior to
21.3R3-S5;
prior to
21.4R3-S4;
prior to
22.1R3-S3;
prior to
22.2R3-S1;
prior to
22.3R2-S2, 22.3R3;
prior to
22.4R2-S1, 22.4R3.
| Software | From | Fixed in |
|---|---|---|
| juniper / junos | - | 20.4 |
| juniper / junos | 20.4-r3-s5 | 20.4-r3-s5.x |
| juniper / junos | 20.4-r3-s4 | 20.4-r3-s4.x |
| juniper / junos | 20.4-r1 | 20.4-r1.x |
| juniper / junos | 20.4-r1-s1 | 20.4-r1-s1.x |
| juniper / junos | 20.4-r2 | 20.4-r2.x |
| juniper / junos | 20.4-r2-s1 | 20.4-r2-s1.x |
| juniper / junos | 20.4-r3 | 20.4-r3.x |
| juniper / junos | 20.4-r3-s1 | 20.4-r3-s1.x |
| juniper / junos | 20.4-r2-s2 | 20.4-r2-s2.x |
| juniper / junos | 20.4 | 20.4.x |
| juniper / junos | 20.4-r3-s2 | 20.4-r3-s2.x |
| juniper / junos | 20.4-r3-s3 | 20.4-r3-s3.x |
| juniper / junos | 20.4-r3-s7 | 20.4-r3-s7.x |
| juniper / junos | 20.4-r3-s6 | 20.4-r3-s6.x |
| juniper / junos | 21.1-r3-s5 | 21.1-r3-s5.x |
| juniper / junos | 21.1-r3-s1 | 21.1-r3-s1.x |
| juniper / junos | 21.1-r2 | 21.1-r2.x |
| juniper / junos | 21.1-r2-s2 | 21.1-r2-s2.x |
| juniper / junos | 21.1-r3 | 21.1-r3.x |
| juniper / junos | 21.1-r2-s1 | 21.1-r2-s1.x |
| juniper / junos | 21.1-r1-s1 | 21.1-r1-s1.x |
| juniper / junos | 21.1-r1 | 21.1-r1.x |
| juniper / junos | 21.1-r3-s2 | 21.1-r3-s2.x |
| juniper / junos | 21.1-r3-s3 | 21.1-r3-s3.x |
| juniper / junos | 21.1-r3-s4 | 21.1-r3-s4.x |
| juniper / junos | 21.2-r3-s2 | 21.2-r3-s2.x |
| juniper / junos | 21.2-r3-s1 | 21.2-r3-s1.x |
| juniper / junos | 21.2-r3-s3 | 21.2-r3-s3.x |
| juniper / junos | 21.2-r1 | 21.2-r1.x |
| juniper / junos | 21.2-r1-s1 | 21.2-r1-s1.x |
| juniper / junos | 21.2 | 21.2.x |
| juniper / junos | 21.2-r1-s2 | 21.2-r1-s2.x |
| juniper / junos | 21.2-r2-s1 | 21.2-r2-s1.x |
| juniper / junos | 21.2-r2-s2 | 21.2-r2-s2.x |
| juniper / junos | 21.2-r2 | 21.2-r2.x |
| juniper / junos | 21.2-r3 | 21.2-r3.x |
| juniper / junos | 21.2-r3-s4 | 21.2-r3-s4.x |
| juniper / junos | 21.2-r3-s5 | 21.2-r3-s5.x |
| juniper / junos | 21.3-r1-s1 | 21.3-r1-s1.x |
| juniper / junos | 21.3-r1-s2 | 21.3-r1-s2.x |
| juniper / junos | 21.3-r2-s1 | 21.3-r2-s1.x |
| juniper / junos | 21.3-r2-s2 | 21.3-r2-s2.x |
| juniper / junos | 21.3-r3 | 21.3-r3.x |
| juniper / junos | 21.3-r3-s1 | 21.3-r3-s1.x |
| juniper / junos | 21.3-r1 | 21.3-r1.x |
| juniper / junos | 21.3-r2 | 21.3-r2.x |
| juniper / junos | 21.3-r3-s3 | 21.3-r3-s3.x |
| juniper / junos | 21.3-r3-s4 | 21.3-r3-s4.x |
| juniper / junos | 21.3-r3-s2 | 21.3-r3-s2.x |
| juniper / junos | 21.3 | 21.3.x |
| juniper / junos | 21.4-r2-s2 | 21.4-r2-s2.x |
| juniper / junos | 21.4-r3 | 21.4-r3.x |
| juniper / junos | 21.4-r3-s3 | 21.4-r3-s3.x |
| juniper / junos | 21.4-r3-s2 | 21.4-r3-s2.x |
| juniper / junos | 21.4-r3-s1 | 21.4-r3-s1.x |
| juniper / junos | 21.4-r1-s1 | 21.4-r1-s1.x |
| juniper / junos | 21.4-r2 | 21.4-r2.x |
| juniper / junos | 21.4-r2-s1 | 21.4-r2-s1.x |
| juniper / junos | 21.4-r1-s2 | 21.4-r1-s2.x |
| juniper / junos | 21.4 | 21.4.x |
| juniper / junos | 21.4-r1 | 21.4-r1.x |
| juniper / junos | 22.1-r1 | 22.1-r1.x |
| juniper / junos | 22.1-r3 | 22.1-r3.x |
| juniper / junos | 22.1-r2-s1 | 22.1-r2-s1.x |
| juniper / junos | 22.1-r3-s2 | 22.1-r3-s2.x |
| juniper / junos | 22.1-r1-s2 | 22.1-r1-s2.x |
| juniper / junos | 22.1-r2-s2 | 22.1-r2-s2.x |
| juniper / junos | 22.1-r1-s1 | 22.1-r1-s1.x |
| juniper / junos | 22.1-r2 | 22.1-r2.x |
| juniper / junos | 22.1-r3-s1 | 22.1-r3-s1.x |
| juniper / junos | 22.2-r1 | 22.2-r1.x |
| juniper / junos | 22.2-r1-s1 | 22.2-r1-s1.x |
| juniper / junos | 22.2-r2 | 22.2-r2.x |
| juniper / junos | 22.2-r2-s2 | 22.2-r2-s2.x |
| juniper / junos | 22.2-r3 | 22.2-r3.x |
| juniper / junos | 22.2-r2-s1 | 22.2-r2-s1.x |
| juniper / junos | 22.2-r1-s2 | 22.2-r1-s2.x |
| juniper / junos | 22.3-r1-s1 | 22.3-r1-s1.x |
| juniper / junos | 22.3-r2-s1 | 22.3-r2-s1.x |
| juniper / junos | 22.3-r1-s2 | 22.3-r1-s2.x |
| juniper / junos | 22.3-r2 | 22.3-r2.x |
| juniper / junos | 22.3-r1 | 22.3-r1.x |
| juniper / junos | 22.4-r1-s1 | 22.4-r1-s1.x |
| juniper / junos | 22.4-r1-s2 | 22.4-r1-s2.x |
| juniper / junos | 22.4-r2 | 22.4-r2.x |
| juniper / junos | 22.4-r1 | 22.4-r1.x |
| juniper / junos | 22.1 | 22.1.x |
| juniper / junos | 22.2 | 22.2.x |
| juniper / junos | 22.3 | 22.3.x |
| juniper / junos | 22.4 | 22.4.x |
A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.
CVSS (Common Vulnerability Scoring System) estimates technical severity, but it doesn't automatically equal business risk. Prioritize using context like internet exposure, affected asset criticality, known exploitation (proof-of-concept or in-the-wild), and whether compensating controls exist. A "Medium" CVSS on an exposed, production system can be more urgent than a "Critical" on an isolated, non-production host.
A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. In practice, risk increases sharply when exploitation becomes reliable or widespread.
Recurring findings usually come from incomplete Asset Discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host. Unknown or unmanaged assets (often called Shadow IT) are a common reason the same issues resurface.
Use a simple, repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress using consistent metrics so remediation is steady, not reactive.
SynScan combines attack surface monitoring and continuous security auditing to keep your inventory current, flag high-impact vulnerabilities early, and help you turn raw findings into a practical remediation plan.