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VulnerabilityPublished

CVE-2025-52952: Juniper Networks Junos OS · Out-of-bounds Write

Affects Juniper Networks Junos OSSource CVE Database V5

0

Not known to be exploited · CVSS 6.5 Medium : upgrade to 22.4R2 or 22.2R3-S1 when convenient.

Data as of 26 Oct 2026, 14:05 UTC

CVSS 3.1 base score
6.5Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.3% chance of exploitation in 30 days – higher than 23% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 22.4R2, 22.2R3-S1
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 11 Jul 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade Juniper Networks Junos OS to 22.4R2 or 22.2R3-S1.

Affected software

ProductAffectedFixed in
Juniper Networks Junos OSAffected
  • =22.4
  • <22.2R3-S1
  • >=22.4 <22.4R2
Fixed in
  • 22.2R3-S1
  • 22.4R2

AI-suggested

To mitigate this vulnerability, European organizations should first verify whether the CFM feature is enabled on their Juniper MX Series routers. If it is not required, disabling the CFM daemon will effectively eliminate the attack surface. For environments where CFM is necessary, organizations should upgrade affected Junos OS versions to 22.2R3-S1 or later, or 22.4R2 or later, as these versions contain fixes for the vulnerability. Network segmentation and strict access controls should be implemented to limit adjacency exposure, ensuring that only trusted devices and users have Layer 2 access to the routers. Monitoring network traffic for malformed CFM packets can help detect attempted exploitation. Additionally, implementing rate limiting or filtering on CFM traffic at network boundaries can reduce the risk of sustained DoS conditions. Regularly reviewing and applying Juniper security advisories and patches is critical to maintaining protection against emerging threats.

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.

References

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