An Improper Check for Unusual or Exceptional Conditions vulnerability in the Juniper DHCP service (jdhcpd) of Juniper Networks Junos OS and Junos OS Evolved allows a DHCP client in one subnet to exhaust the address pools of other subnets, leading to a Denial of Service (DoS) on the downstream DHCP server.
By default, the DHCP relay agent inserts its own Option 82 information when forwarding client requests, optionally replacing any Option 82 information provided by the client. When a specific DHCP DISCOVER is received in 'forward-only' mode with Option 82, the device should drop the message unless 'trust-option82' is configured. Instead, the DHCP relay forwards these packets to the DHCP server unmodified, which uses up addresses in the DHCP server's address pool, ultimately leading to address pool exhaustion.
This issue affects Junos OS:
Junos OS Evolved:
| Software | From | Fixed in |
|---|---|---|
| juniper / junos | - | 21.2 |
| juniper / junos | 21.2 | 21.2.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-r1-s2 | 21.2-r1-s2.x |
| juniper / junos | 21.2-r2 | 21.2-r2.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-r3 | 21.2-r3.x |
| juniper / junos | 21.2-r3-s1 | 21.2-r3-s1.x |
| juniper / junos | 21.2-r3-s2 | 21.2-r3-s2.x |
| juniper / junos | 21.2-r3-s3 | 21.2-r3-s3.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 | 21.2-r3-s6 | 21.2-r3-s6.x |
| juniper / junos | 21.2-r3-s7 | 21.2-r3-s7.x |
| juniper / junos | 21.2-r3-s8 | 21.2-r3-s8.x |
| juniper / junos | 21.2-r3-s9 | 21.2-r3-s9.x |
| juniper / junos | 21.4 | 21.4.x |
| juniper / junos | 21.4-r1 | 21.4-r1.x |
| juniper / junos | 21.4-r1-s1 | 21.4-r1-s1.x |
| juniper / junos | 21.4-r1-s2 | 21.4-r1-s2.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-r2-s2 | 21.4-r2-s2.x |
| juniper / junos | 21.4-r3 | 21.4-r3.x |
| juniper / junos | 21.4-r3-s1 | 21.4-r3-s1.x |
| juniper / junos | 21.4-r3-s10 | 21.4-r3-s10.x |
| juniper / junos | 21.4-r3-s11 | 21.4-r3-s11.x |
| juniper / junos | 21.4-r3-s2 | 21.4-r3-s2.x |
| juniper / junos | 21.4-r3-s3 | 21.4-r3-s3.x |
| juniper / junos | 21.4-r3-s4 | 21.4-r3-s4.x |
| juniper / junos | 21.4-r3-s5 | 21.4-r3-s5.x |
| juniper / junos | 21.4-r3-s6 | 21.4-r3-s6.x |
| juniper / junos | 21.4-r3-s7 | 21.4-r3-s7.x |
| juniper / junos | 21.4-r3-s8 | 21.4-r3-s8.x |
| juniper / junos | 21.4-r3-s9 | 21.4-r3-s9.x |
| juniper / junos | 22.2 | 22.2.x |
| juniper / junos | 22.4 | 22.4.x |
| juniper / junos | 22.4-r1 | 22.4-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-r2-s1 | 22.4-r2-s1.x |
| juniper / junos | 22.4-r2-s2 | 22.4-r2-s2.x |
| juniper / junos | 22.4-r3 | 22.4-r3.x |
| juniper / junos | 22.4-r3-s1 | 22.4-r3-s1.x |
| juniper / junos | 22.4-r3-s2 | 22.4-r3-s2.x |
| juniper / junos | 22.4-r3-s3 | 22.4-r3-s3.x |
| juniper / junos | 22.4-r3-s4 | 22.4-r3-s4.x |
| juniper / junos | 22.4-r3-s5 | 22.4-r3-s5.x |
| juniper / junos | 22.4-r3-s6 | 22.4-r3-s6.x |
| juniper / junos | 22.4-r3-s7 | 22.4-r3-s7.x |
| juniper / junos | 23.2 | 23.2.x |
| juniper / junos | 23.2-r1 | 23.2-r1.x |
| juniper / junos | 23.2-r1-s1 | 23.2-r1-s1.x |
| juniper / junos | 23.2-r1-s2 | 23.2-r1-s2.x |
| juniper / junos | 23.2-r2 | 23.2-r2.x |
| juniper / junos | 23.2-r2-s1 | 23.2-r2-s1.x |
| juniper / junos | 23.2-r2-s2 | 23.2-r2-s2.x |
| juniper / junos | 23.2-r2-s3 | 23.2-r2-s3.x |
| juniper / junos | 23.2-r2-s4 | 23.2-r2-s4.x |
| juniper / junos | 23.4 | 23.4.x |
| juniper / junos | 23.4-r1 | 23.4-r1.x |
| juniper / junos | 23.4-r1-s1 | 23.4-r1-s1.x |
| juniper / junos | 23.4-r1-s2 | 23.4-r1-s2.x |
| juniper / junos | 23.4-r2 | 23.4-r2.x |
| juniper / junos | 23.4-r2-s1 | 23.4-r2-s1.x |
| juniper / junos | 23.4-r2-s2 | 23.4-r2-s2.x |
| juniper / junos | 23.4-r2-s3 | 23.4-r2-s3.x |
| juniper / junos | 23.4-r2-s4 | 23.4-r2-s4.x |
| juniper / junos | 23.4-r2-s5 | 23.4-r2-s5.x |
| juniper / junos | 24.2 | 24.2.x |
| juniper / junos | 24.2-r1 | 24.2-r1.x |
| juniper / junos | 24.2-r1-s1 | 24.2-r1-s1.x |
| juniper / junos | 24.2-r1-s2 | 24.2-r1-s2.x |
| juniper / junos | 24.2-r2 | 24.2-r2.x |
| juniper / junos | 24.2-r2-s1 | 24.2-r2-s1.x |
| juniper / junos | 24.4 | 24.4.x |
| juniper / junos | 24.4-r1 | 24.4-r1.x |
| juniper / junos | 24.4-r1-s2 | 24.4-r1-s2.x |
| juniper / junos | 24.4-r1-s3 | 24.4-r1-s3.x |
| juniper / junos | 25.2 | 25.2.x |
| juniper / junos | 25.2-r1 | 25.2-r1.x |
| juniper / junos | 25.2-r2 | 25.2-r2.x |
| juniper / junos_os_evolved | - | 21.4 |
| juniper / junos_os_evolved | 21.4 | 21.4.x |
| juniper / junos_os_evolved | 21.4-r1 | 21.4-r1.x |
| juniper / junos_os_evolved | 21.4-r1-s1 | 21.4-r1-s1.x |
| juniper / junos_os_evolved | 21.4-r1-s2 | 21.4-r1-s2.x |
| juniper / junos_os_evolved | 21.4-r2 | 21.4-r2.x |
| juniper / junos_os_evolved | 21.4-r2-s1 | 21.4-r2-s1.x |
| juniper / junos_os_evolved | 21.4-r2-s2 | 21.4-r2-s2.x |
| juniper / junos_os_evolved | 21.4-r3 | 21.4-r3.x |
| juniper / junos_os_evolved | 21.4-r3-s1 | 21.4-r3-s1.x |
| juniper / junos_os_evolved | 21.4-r3-s10 | 21.4-r3-s10.x |
| juniper / junos_os_evolved | 21.4-r3-s11 | 21.4-r3-s11.x |
| juniper / junos_os_evolved | 21.4-r3-s2 | 21.4-r3-s2.x |
| juniper / junos_os_evolved | 21.4-r3-s3 | 21.4-r3-s3.x |
| juniper / junos_os_evolved | 21.4-r3-s4 | 21.4-r3-s4.x |
| juniper / junos_os_evolved | 21.4-r3-s5 | 21.4-r3-s5.x |
| juniper / junos_os_evolved | 21.4-r3-s6 | 21.4-r3-s6.x |
| juniper / junos_os_evolved | 21.4-r3-s7 | 21.4-r3-s7.x |
| juniper / junos_os_evolved | 21.4-r3-s8 | 21.4-r3-s8.x |
| juniper / junos_os_evolved | 21.4-r3-s9 | 21.4-r3-s9.x |
| juniper / junos_os_evolved | 22.2 | 22.2.x |
| juniper / junos_os_evolved | 22.4 | 22.4.x |
| juniper / junos_os_evolved | 22.4-r1 | 22.4-r1.x |
| juniper / junos_os_evolved | 22.4-r1-s1 | 22.4-r1-s1.x |
| juniper / junos_os_evolved | 22.4-r1-s2 | 22.4-r1-s2.x |
| juniper / junos_os_evolved | 22.4-r2 | 22.4-r2.x |
| juniper / junos_os_evolved | 22.4-r2-s1 | 22.4-r2-s1.x |
| juniper / junos_os_evolved | 22.4-r2-s2 | 22.4-r2-s2.x |
| juniper / junos_os_evolved | 22.4-r3 | 22.4-r3.x |
| juniper / junos_os_evolved | 22.4-r3-s1 | 22.4-r3-s1.x |
| juniper / junos_os_evolved | 22.4-r3-s2 | 22.4-r3-s2.x |
| juniper / junos_os_evolved | 22.4-r3-s3 | 22.4-r3-s3.x |
| juniper / junos_os_evolved | 22.4-r3-s4 | 22.4-r3-s4.x |
| juniper / junos_os_evolved | 22.4-r3-s5 | 22.4-r3-s5.x |
| juniper / junos_os_evolved | 22.4-r3-s6 | 22.4-r3-s6.x |
| juniper / junos_os_evolved | 22.4-r3-s7 | 22.4-r3-s7.x |
| juniper / junos_os_evolved | 23.2 | 23.2.x |
| juniper / junos_os_evolved | 23.2-r1 | 23.2-r1.x |
| juniper / junos_os_evolved | 23.2-r1-s1 | 23.2-r1-s1.x |
| juniper / junos_os_evolved | 23.2-r1-s2 | 23.2-r1-s2.x |
| juniper / junos_os_evolved | 23.2-r2 | 23.2-r2.x |
| juniper / junos_os_evolved | 23.2-r2-s1 | 23.2-r2-s1.x |
| juniper / junos_os_evolved | 23.2-r2-s2 | 23.2-r2-s2.x |
| juniper / junos_os_evolved | 23.2-r2-s3 | 23.2-r2-s3.x |
| juniper / junos_os_evolved | 23.2-r2-s4 | 23.2-r2-s4.x |
| juniper / junos_os_evolved | 23.4 | 23.4.x |
| juniper / junos_os_evolved | 23.4-r1 | 23.4-r1.x |
| juniper / junos_os_evolved | 23.4-r1-s1 | 23.4-r1-s1.x |
| juniper / junos_os_evolved | 23.4-r1-s2 | 23.4-r1-s2.x |
| juniper / junos_os_evolved | 23.4-r2 | 23.4-r2.x |
| juniper / junos_os_evolved | 23.4-r2-s1 | 23.4-r2-s1.x |
| juniper / junos_os_evolved | 23.4-r2-s2 | 23.4-r2-s2.x |
| juniper / junos_os_evolved | 23.4-r2-s3 | 23.4-r2-s3.x |
| juniper / junos_os_evolved | 23.4-r2-s4 | 23.4-r2-s4.x |
| juniper / junos_os_evolved | 23.4-r2-s5 | 23.4-r2-s5.x |
| juniper / junos_os_evolved | 24.2 | 24.2.x |
| juniper / junos_os_evolved | 24.2-r1 | 24.2-r1.x |
| juniper / junos_os_evolved | 24.2-r1-s2 | 24.2-r1-s2.x |
| juniper / junos_os_evolved | 24.2-r2 | 24.2-r2.x |
| juniper / junos_os_evolved | 24.2-r2-s1 | 24.2-r2-s1.x |
| juniper / junos_os_evolved | 24.4 | 24.4.x |
| juniper / junos_os_evolved | 24.4-r1 | 24.4-r1.x |
| juniper / junos_os_evolved | 24.4-r1-s2 | 24.4-r1-s2.x |
| juniper / junos_os_evolved | 24.4-r1-s3 | 24.4-r1-s3.x |
| juniper / junos_os_evolved | 25.2 | 25.2.x |
| juniper / junos_os_evolved | 25.2-r1 | 25.2-r1.x |
| juniper / junos_os_evolved | 25.2-r2 | 25.2-r2.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.