CVE intelligence and bounded remediation

CVE-2025-21595 — Juniper Junos security vulnerability

High CVSS 7.1

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 befo…

Severity
High
CVSS
7.1 (4.0)
Published
2025-04-09
CISA KEV
Not currently listed
Ecosystem
operating-system
Weaknesses
CWE-401

Affected products

  • juniper / junos
  • juniper / junos / 21.2

Showing 2 representative product identities from 100 source matches. Confirm exact affected versions with the linked vendor and NVD evidence.

Matched remediation archetype

Resource exhaustion and denial of service

This catalog composition supplies bounded fallback guidance. Explicitly reviewed curated workflows load with the complete record below.

Check exposure

  • Identify attacker-influenced work factors including input size, nesting, compression, fan-out, regex cost, allocation, recursion, retries, and connection lifetime.
  • Map per-request and shared CPU, memory, disk, descriptor, thread, queue, and downstream-service limits.
  • Determine whether authentication, tenancy, quotas, and rate controls apply before expensive processing begins.

Remediate safely

  • Bound input size, nesting, expansion, work, concurrency, queue depth, retries, and execution time before resource-intensive processing.
  • Release resources on every success, error, cancellation, and timeout path and use backpressure instead of unbounded buffering.
  • Update affected components and add small deterministic tests that assert resource ceilings rather than exhausting a host.

Authoritative sources

Complete CVE record and remediation plan

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