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

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

Published: 2025-04-09 Last update: 2025-08-11 Assigner: [email protected] Source: [email protected]

Conclusion & alert: CVE-2025-21601 is rated Moderate Risk (57.4/100): CVSS High severity, with medium exploitation likelihood (EPSS 0.45%). Mandatory action: Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2025-21601

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-05-24 0.27% 0.45% +0.18%
2 2026-05-18 0.47% 0.27% -0.20%
3 2026-02-03 0.47%

Full EPSS history (11 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2025-21601

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
8.7 4.0 HIGH
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:Y/R:A/V:C/RE:M/U:Amber Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network.
Attack complexity (AC:L)
Exploitation conditions are straightforward and stable.
Attack requirements (AT:N)
No additional preconditions are required beyond normal reachability.
Privileges required (PR:N)
No privileges are required.
User interaction (UI:N)
No user interaction is required.
Vulnerable system confidentiality impact (VC:N)
No confidentiality impact on the vulnerable system.
Vulnerable system integrity impact (VI:N)
No integrity impact on the vulnerable system.
Vulnerable system availability impact (VA:H)
High availability impact on the vulnerable system.
Subsequent system confidentiality impact (SC:N)
No confidentiality impact on subsequent systems.
Subsequent system integrity impact (SI:N)
No integrity impact on subsequent systems.
Subsequent system availability impact (SA:L)
Limited availability impact on subsequent systems.
Exploit maturity (threat) (E:X)
Not defined: no reliable threat intelligence; scoring assumes the worst case (equivalent to Attacked).
Confidentiality requirement (CR:X)
Not defined: insufficient information; scoring treats this like High (worst case).
Integrity requirement (IR:X)
Not defined: insufficient information; scoring treats this like High (worst case).
Availability requirement (AR:X)
Not defined: insufficient information; scoring treats this like High (worst case).
Modified attack vector (MAV:X)
Not defined: scoring uses the Base Attack Vector (AV).
Modified attack complexity (MAC:X)
Not defined: scoring uses the Base Attack Complexity (AC).
Modified attack requirements (MAT:X)
Not defined: scoring uses the Base Attack Requirements (AT).
Modified privileges required (MPR:X)
Not defined: scoring uses the Base Privileges Required (PR).
Modified user interaction (MUI:X)
Not defined: scoring uses the Base User Interaction (UI).
Modified vulnerable system confidentiality impact (MVC:X)
Not defined: scoring uses the Base VC metric.
Modified vulnerable system integrity impact (MVI:X)
Not defined: scoring uses the Base VI metric.
Modified vulnerable system availability impact (MVA:X)
Not defined: scoring uses the Base VA metric.
Modified subsequent system confidentiality impact (MSC:X)
Not defined: scoring uses the Base SC metric.
Modified subsequent system integrity impact (MSI:X)
Not defined: scoring uses the Base SI metric.
Modified subsequent system availability impact (MSA:X)
Not defined: scoring uses the Base SA metric.
Safety (supplemental) (S:X)
Not evaluated.
Automatable (supplemental) (AU:Y)
Yes: all four kill-chain steps (reconnaissance, weaponization, delivery, exploitation) can be automated.
Recovery (supplemental) (R:A)
Automatic: services recover on their own after an attack.
Value density (supplemental) (V:C)
Concentrated: a single exploit event controls rich resources (e.g., a central server).
Vulnerability response effort (supplemental) (RE:M)
Moderate effort (remote update, disable subsystem, simple upgrade with minor service impact).
Provider urgency (supplemental) (U:AMBER)
Amber: provider rates moderate urgency.
[email protected]
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
3.9 3.6 [email protected]

Weakness enumeration for CVE-2025-21601

Affected software / configurations for CVE-2025-21601

Vendor Product Version Raw CPE
juniper junos <= 21.4 cpe:2.3:o:juniper:junos:*:*:*:*:*:*:*:*
juniper junos 21.4 cpe:2.3:o:juniper:junos:21.4:r1:*:*:*:*:*:*
juniper junos 21.4 cpe:2.3:o:juniper:junos:21.4:r1-s1:*:*:*:*:*:*
juniper junos 21.4 cpe:2.3:o:juniper:junos:21.4:r1-s2:*:*:*:*:*:*
juniper junos 21.4 cpe:2.3:o:juniper:junos:21.4:r2:*:*:*:*:*:*
juniper junos 21.4 cpe:2.3:o:juniper:junos:21.4:r2-s1:*:*:*:*:*:*
juniper junos 21.4 cpe:2.3:o:juniper:junos:21.4:r2-s2:*:*:*:*:*:*
juniper junos 21.4 cpe:2.3:o:juniper:junos:21.4:r3:*:*:*:*:*:*
juniper junos 21.4 cpe:2.3:o:juniper:junos:21.4:r3-s1:*:*:*:*:*:*
juniper junos 21.4 cpe:2.3:o:juniper:junos:21.4:r3-s2:*:*:*:*:*:*
juniper junos 21.4 cpe:2.3:o:juniper:junos:21.4:r3-s3:*:*:*:*:*:*
juniper junos 21.4 cpe:2.3:o:juniper:junos:21.4:r3-s4:*:*:*:*:*:*
juniper junos 21.4 cpe:2.3:o:juniper:junos:21.4:r3-s5:*:*:*:*:*:*
juniper junos 21.4 cpe:2.3:o:juniper:junos:21.4:r3-s6:*:*:*:*:*:*
juniper junos 21.4 cpe:2.3:o:juniper:junos:21.4:r3-s7:*:*:*:*:*:*
juniper junos 21.4 cpe:2.3:o:juniper:junos:21.4:r3-s8:*:*:*:*:*:*
juniper junos 22.2 cpe:2.3:o:juniper:junos:22.2:-:*:*:*:*:*:*
juniper junos 22.2 cpe:2.3:o:juniper:junos:22.2:r1:*:*:*:*:*:*
juniper junos 22.2 cpe:2.3:o:juniper:junos:22.2:r1-s1:*:*:*:*:*:*
juniper junos 22.2 cpe:2.3:o:juniper:junos:22.2:r1-s2:*:*:*:*:*:*
juniper junos 22.2 cpe:2.3:o:juniper:junos:22.2:r2:*:*:*:*:*:*
juniper junos 22.2 cpe:2.3:o:juniper:junos:22.2:r2-s1:*:*:*:*:*:*
juniper junos 22.2 cpe:2.3:o:juniper:junos:22.2:r2-s2:*:*:*:*:*:*
juniper junos 22.2 cpe:2.3:o:juniper:junos:22.2:r3:*:*:*:*:*:*
juniper junos 22.2 cpe:2.3:o:juniper:junos:22.2:r3-s1:*:*:*:*:*:*
juniper junos 22.2 cpe:2.3:o:juniper:junos:22.2:r3-s2:*:*:*:*:*:*
juniper junos 22.2 cpe:2.3:o:juniper:junos:22.2:r3-s3:*:*:*:*:*:*
juniper junos 22.2 cpe:2.3:o:juniper:junos:22.2:r3-s4:*:*:*:*:*:*
juniper junos 22.4 cpe:2.3:o:juniper:junos:22.4:-:*:*:*:*:*:*
juniper junos 22.4 cpe:2.3:o:juniper:junos:22.4:r1:*:*:*:*:*:*
juniper junos 22.4 cpe:2.3:o:juniper:junos:22.4:r1-s1:*:*:*:*:*:*
juniper junos 22.4 cpe:2.3:o:juniper:junos:22.4:r1-s2:*:*:*:*:*:*
juniper junos 22.4 cpe:2.3:o:juniper:junos:22.4:r2:*:*:*:*:*:*
juniper junos 22.4 cpe:2.3:o:juniper:junos:22.4:r2-s1:*:*:*:*:*:*
juniper junos 22.4 cpe:2.3:o:juniper:junos:22.4:r2-s2:*:*:*:*:*:*
juniper junos 22.4 cpe:2.3:o:juniper:junos:22.4:r3:*:*:*:*:*:*
juniper junos 22.4 cpe:2.3:o:juniper:junos:22.4:r3-s1:*:*:*:*:*:*
juniper junos 22.4 cpe:2.3:o:juniper:junos:22.4:r3-s2:*:*:*:*:*:*
juniper junos 22.4 cpe:2.3:o:juniper:junos:22.4:r3-s3:*:*:*:*:*:*
juniper junos 23.2 cpe:2.3:o:juniper:junos:23.2:-:*:*:*:*:*:*
juniper junos 23.2 cpe:2.3:o:juniper:junos:23.2:r1:*:*:*:*:*:*
juniper junos 23.2 cpe:2.3:o:juniper:junos:23.2:r1-s1:*:*:*:*:*:*
juniper junos 23.2 cpe:2.3:o:juniper:junos:23.2:r1-s2:*:*:*:*:*:*
juniper junos 23.2 cpe:2.3:o:juniper:junos:23.2:r2:*:*:*:*:*:*
juniper junos 23.2 cpe:2.3:o:juniper:junos:23.2:r2-s1:*:*:*:*:*:*
juniper junos 23.2 cpe:2.3:o:juniper:junos:23.2:r2-s2:*:*:*:*:*:*
juniper junos 23.4 cpe:2.3:o:juniper:junos:23.4:-:*:*:*:*:*:*
juniper junos 23.4 cpe:2.3:o:juniper:junos:23.4:r1:*:*:*:*:*:*
juniper junos 23.4 cpe:2.3:o:juniper:junos:23.4:r1-s1:*:*:*:*:*:*
juniper junos 23.4 cpe:2.3:o:juniper:junos:23.4:r1-s2:*:*:*:*:*:*
juniper junos 23.4 cpe:2.3:o:juniper:junos:23.4:r2:*:*:*:*:*:*
juniper junos 23.4 cpe:2.3:o:juniper:junos:23.4:r2-s1:*:*:*:*:*:*
juniper junos 23.4 cpe:2.3:o:juniper:junos:23.4:r2-s2:*:*:*:*:*:*
juniper junos 24.2 cpe:2.3:o:juniper:junos:24.2:-:*:*:*:*:*:*
juniper junos 24.2 cpe:2.3:o:juniper:junos:24.2:r1:*:*:*:*:*:*

References for CVE-2025-21601

cvelogic Threat Intelligence