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
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.
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)
CVSS metrics for this CVE.
| Base score | Version | Severity | Vector | Exploitability | Impact | Score source |
|---|---|---|---|---|---|---|
| 8.7 | 4.0 | HIGH |
|
— | — | [email protected] |
| 7.5 | 3.1 | HIGH |
|
3.9 | 3.6 | [email protected] |
| 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:*:*:*:*:*:* |
| URL | Tags |
|---|---|
| https://supportportal.juniper.net/JSA96452 | Vendor Advisory |