CVE-2026-21902: Junos OS Evolved: PTX Series: A vulnerability allows a unauthenticated, network-based attacker to execute code as root
- Is it exploited?
Reported, not confirmed by CISA. VulnCheck KEV lists it as exploited in the wild. CISA has not added it to its Known Exploited Vulnerabilities catalog as of .
VulnCheck KEV lists it since . It cites 17 public reports, the first from . VulnCheck's own honeypots also recorded exploitation attempts.
- How likely is exploitation in the next 30 days?
- 18.5%
Up from 18.4% on .
EPSS score, percentile 97.2 of all scored records. A probability estimated by FIRST, not a report of exploitation.
CISA's SSVC assessment in the CVE record lists exploitation as poc.
- How severe?
- 9.3 Critical
CVSS v4.0 base score, given by the CNA
- What should I do?
The following software releases have been updated to resolve this specific issue: 25.4R1-S1-EVO, 25.4R2-EVO*, 26.2R1-EVO*, and all subsequent releases. * Future ReleaseSolution from the CVE record.
CISA has set no required action, because the vulnerability is not in KEV.
- Which versions are affected?
Affected
- from 25.4 to before 25.4R1-S1-EVO, 25.4R2-EVO
Unaffected before 25.4R1-EVO
Source: CISA KEV 2026.10.29, as of ; VulnCheck KEV, as of ; FIRST EPSS, as of ; CVE List, as of . About the data.
Description
Junos OS Evolved: PTX Series: A vulnerability allows a unauthenticated, network-based attacker to execute code as root
An Incorrect Permission Assignment for Critical Resource vulnerability in the On-Box Anomaly detection framework of Juniper Networks Junos OS Evolved on PTX Series allows an unauthenticated, network-based attacker to execute code as root. The On-Box Anomaly detection framework should only be reachable by other internal processes over the internal routing instance, but not over an externally exposed port. With the ability to access and manipulate the service to execute code as root a remote attacker can take complete control of the device. Please note that this service is enabled by default as no specific configuration is required. This issue affects Junos OS Evolved on PTX Series: * 25.4 versions before 25.4R1-S1-EVO, 25.4R2-EVO. This issue does not affect Junos OS Evolved versions before 25.4R1-EVO. This issue does not affect Junos OS.
Source: CVE List, as of . About the data.
What to do
Advisories and patches
Workaround (from the CVE record)
To reduce the risk of exploitation of this issue, use access lists or firewall filters to limit access to only trusted networks and hosts. Please ensure such filters only permit explicitly required connections and block all others. Also this service can be disabled by 'request pfe anomalies disable'.
This summary is based on the CVE record as of . Check the vendor's advisory before you act: affected versions and fixes can change.
Affected products and versions
Versions by product, as listed in the CVE record (1 product)
| Status | Versions |
|---|---|
| Affected | from 25.4 to before 25.4R1-S1-EVO, 25.4R2-EVO |
| Unaffected | before 25.4R1-EVO |
Versions not listed are: unaffected.
Source: CVE List, as of . About the data.
Weakness
CWE-732
- CWE-732: Incorrect Permission Assignment for Critical Resource
CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record.
Timeline
| Date | Event |
|---|---|
| CVE record published | |
| CVE record last updated |
Known exploited Juniper vulnerabilities
- CVE-2015-7755: Juniper ScreenOS Improper Authentication Vulnerability
- CVE-2025-21590: Juniper Junos OS Improper Isolation or Compartmentalization Vulnerability
- CVE-2023-36844: Juniper Junos OS EX Series PHP External Variable Modification Vulnerability
- CVE-2023-36845: Juniper Junos OS EX Series and SRX Series PHP External Variable Modification Vulnerability
- CVE-2023-36846: Juniper Junos OS SRX Series Missing Authentication for Critical Function Vulnerability