CVE-2025-52947

Forwarding engine crash via hot-standby interface flap

Published Jul 11, 2025 · Updated Jul 11, 2025

Denial of service in Juniper Networks Junos OS before 21.2R3-S9 allows attackers to crash an ACX Forwarding Engine by flapping an interface. In route processing, a primary-path IGP port-down event for a hot-standby L2 circuit is handled as an exceptional condition that crashes FEB0. Reachability requires adjacency and the affected hot-standby configuration; the result is a forwarding interruption, with no reported data exposure or modification.

CVSS severity7.1
High
EPSS probability0.26%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Juniper Networks Junos OS before 21.2R3-S9 allows attackers to crash an ACX Forwarding Engine by flapping an interface. In route processing, a primary-path IGP port-down event for a hot-standby L2 circuit is handled as an exceptional condition that crashes FEB0. Reachability requires adjacency and the affected hot-standby configuration; the result is a forwarding interruption, with no reported data exposure or modification.

The record

CVE
CVE-2025-52947
Published
Jul 11, 2025
Updated
Jul 11, 2025
Vendor
Juniper Networks
Product
Junos OS
Classifications
CWE-755, T1499.004
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 11, 2025CVE publishedPublication date reported by the CVE source.
  2. Jul 11, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <21.2R3-S9

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Juniper Networks · Junos OSversion=0 <21.2R3-S9

Published CVSS scores

7.1Juniper Networks, Inc.CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/R:A/RE:M/U:Green
6.5Juniper Networks, Inc.CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-755Improper Handling of Exceptional Conditions
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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