CVE-2025-21601Network attack vector

Device hang via web-management CPU exhaustion

Published Apr 9, 2025 · Updated Apr 15, 2025

Denial of service in Juniper Networks Junos OS web management allows remote attackers to make affected devices unresponsive. The affected J-Web, Captive Portal, 802.1X, JSC, and Firewall Authentication paths handle genuine traffic in a way that drives sustained httpd CPU use. Web management for one of these services must be enabled and continuously receive the packets; the result is a sustained device hang, not data access or modification.

CVSS severity8.7
High
EPSS probability0.42%
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 web management allows remote attackers to make affected devices unresponsive. The affected J-Web, Captive Portal, 802.1X, JSC, and Firewall Authentication paths handle genuine traffic in a way that drives sustained httpd CPU use. Web management for one of these services must be enabled and continuously receive the packets; the result is a sustained device hang, not data access or modification.

The record

CVE
CVE-2025-21601
Published
Apr 9, 2025
Updated
Apr 15, 2025
Vendor
Juniper Networks
Product
Junos OS
Classifications
CWE-573, T1499.003
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 9, 2025CVE publishedPublication date reported by the CVE source.
  2. Apr 15, 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 <21.4R3-S9
  2. Affected versionversion=22.2 <22.2R3-S5
  3. Affected versionversion=22.4 <22.4R3-S4
  4. Affected versionversion=23.2 <23.2R2-S3
  5. Affected versionversion=23.4 <23.4R2-S3
  6. Affected versionversion=24.2 <24.2R1-S1, 24.2R2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Juniper Networks · Junos OSversion=0 <21.4R3-S9; version=22.2 <22.2R3-S5; version=22.4 <22.4R3-S4; version=23.2 <23.2R2-S3; version=23.4 <23.4R2-S3; version=24.2 <24.2R1-S1, 24.2R2

Published CVSS scores

8.7Juniper NetworksCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/AU:Y/R:A/V:C/RE:M/U:Amber
7.5Juniper NetworksCVSS:3.1/AV:N/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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

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

Weakness, pattern, technique

CWE-573Improper Following of Specification by Caller
T1499.003Application Exhaustion Flood

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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