CVE-2025-52952: Junos OS: MX Series with MPC-BUILTIN, MPC 1 through MPC 9: Receipt and processing of a malformed packet causes one or more FPCs to crash

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-07-11 · updated 2026-06-17
Weakness: CWE-787

Description

An Out-of-bounds Write vulnerability in the connectivity fault management (CFM) daemon of Juniper Networks Junos OS on MX Series with MPC-BUILTIN, MPC1 through MPC9 line cards allows an unauthenticated adjacent attacker to send a malformed packet to the device, leading to an FPC crash and restart, resulting in a Denial of Service (DoS). Continued receipt and processing of this packet will create a sustained Denial of Service (DoS) condition. This issue affects Juniper Networks: Junos OS: * All versions before 22.2R3-S1, * from 22.4 before 22.4R2. This feature is not enabled by default.

Affected products

Juniper Junos OS: before 22.2; 22.2, 22.2-r1, 22.2-r1-s1, 22.2-r1-s2, 22.2-r2, 22.2-r2-s1 (+6) — fixed in 22.2

How to fix

Upgrade to a fixed version: Juniper Junos OS 22.2. Check the vendor advisory for mitigations.

References

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