An Improper Check for Unusual or Exceptional Conditions vulnerability in routing protocol daemon (rpd) of Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated, logically adjacent BGP peer to cause Denial of Service (DoS).
On all Junos OS and Junos OS Evolved platforms, when BGP rib-sharding and update-threading are configured, and a BGP peer flap is done with specific timing, rpd crashes and restarts. Continuous peer flapping at specific time intervals will result in a sustained Denial of Service (DoS) condition.
This issue affects eBGP and iBGP, in both IPv4 and IPv6 implementations. This issue requires a remote attacker to have at least one established BGP session. The issue can occur with or without logical-systems enabled.
This issue affects: Junos OS:
All versions before 20.4R3-S8,
21.2 versions before 21.2R3-S6,
21.3 versions before 21.3R3-S5,
21.4 versions before 21.4R3-S4,
22.1 versions before 22.1R3-S3,
22.2 versions before 22.2R3-S1,
22.3 versions before 22.3R3,
22.4 versions before 22.4R3.
Junos OS Evolved:
| Software | From | Fixed in |
|---|---|---|
| juniper / junos | - | 20.4 |
| juniper / junos | 20.4 | 20.4.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-r2-s2 | 20.4-r2-s2.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-r3-s2 | 20.4-r3-s2.x |
| juniper / junos | 20.4-r3-s3 | 20.4-r3-s3.x |
| juniper / junos | 20.4-r3-s4 | 20.4-r3-s4.x |
| juniper / junos | 20.4-r3-s5 | 20.4-r3-s5.x |
| juniper / junos | 20.4-r3-s6 | 20.4-r3-s6.x |
| juniper / junos | 20.4-r3-s7 | 20.4-r3-s7.x |
| 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 | 21.3 | 21.3.x |
| juniper / junos | 21.3-r1 | 21.3-r1.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 | 21.3-r2.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-r3-s2 | 21.3-r3-s2.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 | 21.4 | 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-s2 | 21.4-r3-s2.x |
| juniper / junos | 21.4-r3-s3 | 21.4-r3-s3.x |
| juniper / junos | 22.1 | 22.1.x |
| juniper / junos | 22.1-r1 | 22.1-r1.x |
| juniper / junos | 22.1-r1-s1 | 22.1-r1-s1.x |
| juniper / junos | 22.1-r1-s2 | 22.1-r1-s2.x |
| juniper / junos | 22.1-r2 | 22.1-r2.x |
| juniper / junos | 22.1-r2-s1 | 22.1-r2-s1.x |
| juniper / junos | 22.1-r2-s2 | 22.1-r2-s2.x |
| juniper / junos | 22.1-r3 | 22.1-r3.x |
| juniper / junos | 22.1-r3-s1 | 22.1-r3-s1.x |
| juniper / junos | 22.1-r3-s2 | 22.1-r3-s2.x |
| juniper / junos | 22.2 | 22.2.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-r1-s2 | 22.2-r1-s2.x |
| juniper / junos | 22.2-r2 | 22.2-r2.x |
| juniper / junos | 22.2-r2-s1 | 22.2-r2-s1.x |
| juniper / junos | 22.2-r2-s2 | 22.2-r2-s2.x |
| juniper / junos | 22.2-r3 | 22.2-r3.x |
| juniper / junos | 22.3 | 22.3.x |
| juniper / junos | 22.3-r1 | 22.3-r1.x |
| juniper / junos | 22.3-r1-s1 | 22.3-r1-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-r2-s1 | 22.3-r2-s1.x |
| juniper / junos | 22.3-r2-s2 | 22.3-r2-s2.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_os_evolved | - | 21.2 |
| juniper / junos_os_evolved | 21.2 | 21.2.x |
| juniper / junos_os_evolved | 21.2-r1 | 21.2-r1.x |
| juniper / junos_os_evolved | 21.2-r1-s1 | 21.2-r1-s1.x |
| juniper / junos_os_evolved | 21.2-r1-s2 | 21.2-r1-s2.x |
| juniper / junos_os_evolved | 21.2-r2 | 21.2-r2.x |
| juniper / junos_os_evolved | 21.2-r2-s1 | 21.2-r2-s1.x |
| juniper / junos_os_evolved | 21.2-r2-s2 | 21.2-r2-s2.x |
| juniper / junos_os_evolved | 21.2-r3 | 21.2-r3.x |
| juniper / junos_os_evolved | 21.2-r3-s1 | 21.2-r3-s1.x |
| juniper / junos_os_evolved | 21.2-r3-s2 | 21.2-r3-s2.x |
| juniper / junos_os_evolved | 21.2-r3-s3 | 21.2-r3-s3.x |
| juniper / junos_os_evolved | 21.2-r3-s4 | 21.2-r3-s4.x |
| juniper / junos_os_evolved | 21.2-r3-s5 | 21.2-r3-s5.x |
| juniper / junos_os_evolved | 21.3 | 21.3.x |
| juniper / junos_os_evolved | 21.3-r1 | 21.3-r1.x |
| juniper / junos_os_evolved | 21.3-r1-s1 | 21.3-r1-s1.x |
| juniper / junos_os_evolved | 21.3-r2 | 21.3-r2.x |
| juniper / junos_os_evolved | 21.3-r2-s1 | 21.3-r2-s1.x |
| juniper / junos_os_evolved | 21.3-r2-s2 | 21.3-r2-s2.x |
| juniper / junos_os_evolved | 21.3-r3 | 21.3-r3.x |
| juniper / junos_os_evolved | 21.3-r3-s1 | 21.3-r3-s1.x |
| juniper / junos_os_evolved | 21.3-r3-s2 | 21.3-r3-s2.x |
| juniper / junos_os_evolved | 21.3-r3-s3 | 21.3-r3-s3.x |
| juniper / junos_os_evolved | 21.3-r3-s4 | 21.3-r3-s4.x |
| 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-s2 | 21.4-r3-s2.x |
| juniper / junos_os_evolved | 21.4-r3-s3 | 21.4-r3-s3.x |
| juniper / junos_os_evolved | 22.1 | 22.1.x |
| juniper / junos_os_evolved | 22.1-r1 | 22.1-r1.x |
| juniper / junos_os_evolved | 22.1-r1-s1 | 22.1-r1-s1.x |
| juniper / junos_os_evolved | 22.1-r1-s2 | 22.1-r1-s2.x |
| juniper / junos_os_evolved | 22.1-r2 | 22.1-r2.x |
| juniper / junos_os_evolved | 22.1-r2-s1 | 22.1-r2-s1.x |
| juniper / junos_os_evolved | 22.1-r3 | 22.1-r3.x |
| juniper / junos_os_evolved | 22.1-r3-s1 | 22.1-r3-s1.x |
| juniper / junos_os_evolved | 22.1-r3-s2 | 22.1-r3-s2.x |
| juniper / junos_os_evolved | 22.2 | 22.2.x |
| juniper / junos_os_evolved | 22.2-r1 | 22.2-r1.x |
| juniper / junos_os_evolved | 22.2-r1-s1 | 22.2-r1-s1.x |
| juniper / junos_os_evolved | 22.2-r1-s2 | 22.2-r1-s2.x |
| juniper / junos_os_evolved | 22.2-r2 | 22.2-r2.x |
| juniper / junos_os_evolved | 22.2-r2-s1 | 22.2-r2-s1.x |
| juniper / junos_os_evolved | 22.2-r2-s2 | 22.2-r2-s2.x |
| juniper / junos_os_evolved | 22.2-r3 | 22.2-r3.x |
| juniper / junos_os_evolved | 22.3 | 22.3.x |
| juniper / junos_os_evolved | 22.3-r1 | 22.3-r1.x |
| juniper / junos_os_evolved | 22.3-r1-s1 | 22.3-r1-s1.x |
| juniper / junos_os_evolved | 22.3-r1-s2 | 22.3-r1-s2.x |
| juniper / junos_os_evolved | 22.3-r2 | 22.3-r2.x |
| juniper / junos_os_evolved | 22.3-r2-s1 | 22.3-r2-s1.x |
| juniper / junos_os_evolved | 22.3-r2-s2 | 22.3-r2-s2.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 |
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.