CVE-2025-21601

Junos OS: SRX and EX Series, MX240, MX480, MX960, QFX5120 Series: When web management is enabled for specific services an attacker may cause a CPU spike by sending genuine packets to the device

Description

An Improper Following of Specification by Caller vulnerability in web management (J-Web, Captive Portal, 802.1X, Juniper Secure Connect (JSC) of Juniper Networks Junos OS on SRX Series, EX Series, MX240, MX480, MX960, QFX5120 Series, allows an unauthenticated, network-based attacker, sending genuine traffic targeted to the device to cause the CPU to climb until the device becomes unresponsive. Continuous receipt of these packets will create a sustained Denial of Service (DoS) condition. This issue affects Junos OS:  * All versions before 21.4R3-S9, * from 22.2 before 22.2R3-S5, * from 22.4 before 22.4R3-S4, * from 23.2 before 23.2R2-S3, * from 23.4 before 23.4R2-S3, * from 24.2 before 24.2R1-S1, 24.2R2. An indicator of compromise is to review the CPU % of the httpd process in the CLI: e.g.   show system processes extensive | match httpd  PID nobody       52   0   20M    191M select   2   0:01   80.00% httpd{httpd} <<<<< the percentage of httpd usage if high may be an indicator

Remediation

Solution:

  • The following software releases have been updated to resolve this specific issue: Junos OS: 21.4R3-S9, 22.2R3-S5, 22.4R3-S4, 23.2R2-S3, 23.4R2-S3, 24.2R1-S1, 24.2R2, 24.4R1, and all subsequent releases.

Workaround:

  • There are no known workarounds for this issue. To reduce the risk of exploitation use authentication when using web management services.

Category

8.7
CVSS
Severity: High
CVSS 4.0 •
CVSS 3.1 •
EPSS 0.07%
Vendor Advisory juniper.net
Affected: Juniper Networks Junos OS
Published at:
Updated at:

References

Link Tags
https://supportportal.juniper.net/JSA96452 vendor advisory

Frequently Asked Questions

What is the severity of CVE-2025-21601?
CVE-2025-21601 has been scored as a high severity vulnerability.
How to fix CVE-2025-21601?
To fix CVE-2025-21601: The following software releases have been updated to resolve this specific issue: Junos OS: 21.4R3-S9, 22.2R3-S5, 22.4R3-S4, 23.2R2-S3, 23.4R2-S3, 24.2R1-S1, 24.2R2, 24.4R1, and all subsequent releases.
Is CVE-2025-21601 being actively exploited in the wild?
As for now, there are no information to confirm that CVE-2025-21601 is being actively exploited. According to its EPSS score, there is a ~0% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
What software or system is affected by CVE-2025-21601?
CVE-2025-21601 affects Juniper Networks Junos OS.
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