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VulnerabilityPublished

CVE-2025-52947: Juniper Networks Junos OS · Improper Handling of Exceptional Conditions

Affects Juniper Networks Junos OSSource CVE Database V5

0

Not known to be exploited · CVSS 6.5 Medium · end of life, no fix coming : replace or isolate Juniper Networks Junos OS; no fix will be released.

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 22% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
None coming – the product is end of life
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

No fix will be released: Juniper Networks Junos OS is end of life. Replace it, or isolate it from untrusted networks until you can.

Affected software

ProductAffectedFixed in
Juniper Networks Junos OSAffected
  • =0
Fixed in–

AI-suggested

  1. Upgrade affected Junos OS versions to 21.2R3-S9 or later where the vulnerability is fixed. If immediate upgrade is not feasible, consider network segmentation to isolate affected devices from untrusted or less secure network segments to reduce attack surface.
  2. Disable 'hot-standby' mode on L2 circuits if operationally possible, as the vulnerability manifests only when this mode is enabled.
  3. Monitor interface status and logs for unusual flapping behavior that could indicate exploitation attempts.
  4. Implement strict access controls and network segmentation to limit adjacency access to critical Juniper ACX devices.
  5. Develop incident response plans to quickly detect and recover from FEB crashes, including device reboots or failover procedures.
  6. Engage with Juniper Networks support or authorized partners for guidance on patch availability and device upgrade paths given the EOL status of affected hardware.
  7. Consider hardware refresh or migration to supported platforms to reduce exposure to unpatched vulnerabilities and improve long-term security posture.

Description

An Improper Handling of Exceptional Conditions vulnerability in route processing of Juniper Networks Junos OS on specific end-of-life (EOL) ACX Series platforms allows an attacker to crash the Forwarding Engine Board (FEB) by flapping an interface, leading to a Denial of Service (DoS). On ACX1000, ACX1100, ACX2000, ACX2100, ACX2200, ACX4000, ACX5048, and ACX5096 devices, FEB0 will crash when the primary path port of the L2 circuit IGP (Interior Gateway Protocol) on the local device goes down. This issue is seen only when 'hot-standby' mode is configured for the L2 circuit. This issue affects Junos OS on ACX1000, ACX1100, ACX2000, ACX2100, ACX2200, ACX4000, ACX5048, and ACX5096:  * all versions before 21.2R3-S9.

References

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