CVE Intelligence
Critical Access control

CVE-2026-21902 — 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.

Published Feb 25, 2026 · Updated Oct 13, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: juniper

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.
How the score was calculated
  • EPSS 18.4% (30-day exploitation probability)+15
  • Technical severity (critical)+10
  • CISA SSVC: exploitation "poc"+5
  • Automatable exploitation (SSVC)+3

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation
Not confirmed
Not in CISA KEV — an absence of record, not proof it is unexploited.
EPSS FIRST
18.38%
ahead of 97% of scored CVEs · Oct 14, 2026
Affects
Juniper Networks
Junos Os Evolved
CVSS base
9.8
Critical · 2 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation
Proof of concept
none · proof-of-concept · active
Automatable
Yes
can an attacker script the kill-chain steps
Technical impact
Total
partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

  1. Identify exposed assets running the affected vendor/product/version combinations (Juniper Networks Junos Os Evolved).
  2. The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
  3. Apply the documented mitigations until a definitive fix is available.
  4. EPSS ahead of 97% of scored CVEs: prioritize it in the patch queue.
  5. Search available logs for exploit probes matching the vulnerability class (access control), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Juniper Networks Junos Os Evolved version 25.4-r1 Vulnerable NIST National Vulnerability Database
Juniper Networks Junos Os Evolved ≥ 25.4 and < 25.4R1-S1-EVO, 25.4R2-EVO Vulnerable CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactScored by
9.3 CVSS 4.0 Critical — — sirt@juniper.net via NIST National Vulnerability Database
9.3 CVSS 4.0 Critical — — juniper via CVE Program (cve.org) e CISA ADP
9.8 CVSS 3.1 Critical 3.9 5.9 sirt@juniper.net via NIST National Vulnerability Database
9.8 CVSS 3.1 Critical — — juniper via CVE Program (cve.org) e CISA ADP
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H (score shown at the top: sirt@juniper.net)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-732 · Incorrect Permission Assignment for Critical Resource

Other CVEs with this weakness →

EPSS over time FIRST

Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 18.38%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

  • Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
  • Audit administrative actions and access to resources outside each user’s normal pattern.
web/proxy/WAF logsnetwork IDS/IPSauthentication logsapplication logs

Timeline

What happened to this CVE, newest first.

  • 2026
  • Affected products added · juniper networks/junos os evolved
    Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
  • SSVC assessment updated
    Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
  • Record published
    Oct 13, 2026
  • Fix documented
    Oct 13, 2026 · NIST National Vulnerability Database
  • CVSS changed · 9.8
    Oct 13, 2026 · NIST National Vulnerability Database
  • Source status changed · → Analyzed
    Oct 13, 2026 · NIST National Vulnerability Database
  • Record created in this database
    Oct 13, 2026 · NIST National Vulnerability Database
  • CVE published
    Feb 25, 2026 · juniper

Source activity

Repeated readings are counted rather than listed.

  • 1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

3 on the record

Elsewhere on this site

Juniper Networks
every CVE for this vendor
Access control
same class
CWE-732
other pages naming this weakness

Related CVEs (same products)

  • CVE-2026-101982 Junos OS and Junos OS Evolved: A EVPN peer causes an rpd crash or root-level compromise when EVPN-VPWS is used 1d
  • CVE-2026-101983 Junos OS and Junos OS Evolved: An attacker causes remote code execution when J-Web virtual-domain is configured 1d
  • CVE-2026-101979 Junos OS and Junos OS Evolved: A network attacker causes root-level code execution or denial of service when SNMP and AAA are enabled 1d
  • CVE-2026-101976 Junos OS and Junos OS Evolved: In a non-4byte-AS scenario a specific BGP update causes an rpd crash 1d
  • CVE-2026-101972 Junos OS and Junos OS Evolved: Malformed OSPF packets causes routing disruption when OSPF is enabled 1d
  • CVE-2026-101964 Junos OS and Junos OS Evolved: An attacker can cause an rpd crash via a crafted LDP message 1d

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-21902 is "Junos OS Evolved: PTX Series: A vulnerability allows a unauthenticated, network-based attacker to execute code as root", rated Critical. It affects Junos Os Evolved (Juniper Networks); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 9.8 describes technical severity. EPSS 18.38% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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