CVE-2026-21902Junos OS Evolved Vulnerability
Junos OS Evolved: PTX Series: A vulnerability allows a unauthenticated, network-based attacker to execute code as root
Published Feb 25, 2026 · Updated Mar 4, 2026
Key Facts
Patch immediately- CVE-2026-21902 is a critical-severity vulnerability (CVSS 9.3 v4) affecting Junos OS Evolved (Juniper).
- It is exploited in the wild, listed in CIRCL KEV, Industry KEV feed since Mar 14, 2026. A public exploit is reported by tracking sources, but no code link is listed yet.
- EPSS estimates a 18% probability of exploitation in the next 30 days.
- Fixed versions are available, including Junos OS Evolved 25.4R1-S1-EVO, 25.4R2-EVO.
- Brandefense priority: patch immediately, because it is listed as exploited in the wild.
Scores
CVSS v4
9.3
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/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:U/V:X/RE:M/U:Red
EPSS (30-day exploit likelihood)
18%
Higher than 97.2% of all scored CVEs
Exploit maturity
Exploited (KEV)
ATLAS score
68/100
Publication score, see How it works
Exploitation Verdict
KEV listed
Mar 14, 2026
17 days after publication
Federal due date
None
No federal due date
Ransomware use
Not reported
Attributed actors
None named
Exploit & Defence Guidance
Exploit maturity
Exploited (KEV)
Public exploit code
1
Proof-of-concept links
In-the-wild evidence
10
Reports of active use
Advisories And Exploit References
Description
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.
Known-Exploited Catalog Listings
| Catalog | Added | Remediation due | Ransomware use |
|---|---|---|---|
| CIRCL KEV | Mar 14, 2026 | n/a | Not reported |
| Industry KEV feed | Mar 14, 2026 | n/a | Not reported |
Affected Products
2 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| Junos OS EvolvedJuniper | 25.4-r1, >= 25.4 | 25.4R1-S1-EVO, 25.4R2-EVO |
Patched Releases
Junos OS Evolved
25.4R1-S1-EVO, 25.4R2-EVO
Timeline
Publicly disclosed
Feb 25, 2026
Last updated
Mar 4, 2026
Added to CIRCL KEV
Mar 14, 2026
Added to Industry KEV feed
Mar 14, 2026
Weakness Type
- CWE-732 Incorrect Permission Assignment for Critical Resource
References
- advisorykb.juniper.net · JSA107128
- advisorysupportportal.juniper.net · JSA107128
- exploitVulnCheck exploitation report
- exploitVulnCheck exploitation report
- exploitVulnCheck exploitation report
FAQ
Common Questions.
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.
Affected: Junos OS Evolved (Juniper) versions 25.4-r1, >= 25.4. The full list is in the CVE brief.
It is exploited in the wild, listed in CIRCL KEV, Industry KEV feed since Mar 14, 2026.
No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.
A public exploit is reported by tracking sources, but no code link is listed yet.
Fixed versions are available, including Junos OS Evolved 25.4R1-S1-EVO, 25.4R2-EVO.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.
Is CVE-2026-21902 On Your Attack Surface?
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