Vulnerability Database

328,409

Total vulnerabilities in the database

CVE-2025-21595

A Missing Release of Memory after Effective Lifetime vulnerability in the Packet Forwarding Engine (PFE) of Juniper Networks Junos OS and Junos OS Evolved allows an adjacent, unauthenticated attacker to cause an FPC to crash, leading to Denial of Service (DoS).

On all Junos OS and Junos OS Evolved platforms, in an EVPN-VXLAN scenario, when specific ARP packets are received on an IPv4 network, or specific NDP packets are received on an IPv6 network, kernel heap memory leaks, which eventually leads to an FPC crash and restart.

This issue does not affect MX Series platforms. Heap size growth on FPC can be seen using below command.

user@host> show chassis fpc                     Temp CPU Utilization (%) CPU Utilization (%) Memory   Utilization (%) Slot State           (C) Total Interrupt     1min   5min   15min   DRAM (MB)   Heap   Buffer   0 Online           45     3         0       2       2      2       32768      19       0 <<<<<<< Heap increase in all fPCs

This issue affects Junos OS:

  • All versions before 21.2R3-S7,
  • 21.4 versions before 21.4R3-S4,
  • 22.2 versions before 22.2R3-S1, 
  • 22.3 versions before 22.3R3-S1, 
  • 22.4 versions before 22.4R2-S2, 22.4R3.

and Junos OS Evolved:

  • All versions before 21.2R3-S7-EVO,

  • 21.4-EVO versions before 21.4R3-S4-EVO,

  • 22.2-EVO versions before 22.2R3-S1-EVO, 

  • 22.3-EVO versions before 22.3R3-S1-EVO, 

  • 22.4-EVO versions before 22.4R3-EVO.

  • Published: Apr 9, 2025
  • Updated: Nov 16, 2025
  • CVE: CVE-2025-21595
  • Severity: Medium
  • Exploit:

CVSS v3:

  • Severity: Medium
  • Score: 6.5
  • AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CWEs:

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 21.4 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 21.4-r3-s4 21.4-r3-s4.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 22.3-r3 22.3-r3.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-r3 22.4-r3.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 21.2-r3-s6 21.2-r3-s6.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 21.4-r3-s4 21.4-r3-s4.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 22.3-r3 22.3-r3.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

Frequently Asked Questions

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.