Unauthenticated file access via unguarded J-Web endpoint
Published Sep 26, 2023 · Updated Oct 21, 2025
Missing authentication in J-Web on Juniper Networks Junos OS SRX Series allows remote attackers to upload and download arbitrary files. The webauth_operation.php endpoint dispatches its file-transfer operation without checking for an authenticated session, so crafted requests write supplied content to the J-Web jail or retrieve accessible files. J-Web HTTP or HTTPS management must be enabled and network-reachable; the direct consequence is unauthorized file read or write, while code execution requires chaining with another flaw.
Summary
What happened
Missing authentication in J-Web on Juniper Networks Junos OS SRX Series allows remote attackers to upload and download arbitrary files. The webauth_operation.php endpoint dispatches its file-transfer operation without checking for an authenticated session, so crafted requests write supplied content to the J-Web jail or retrieve accessible files. J-Web HTTP or HTTPS management must be enabled and network-reachable; the direct consequence is unauthorized file read or write, while code execution requires chaining with another flaw.
The record
- CVE
- CVE-2023-36851
- Published
- Sep 26, 2023
- Updated
- Oct 21, 2025
- Vendor
- Juniper Networks
- Product
- Junos OS
- Classifications
- CWE-306, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 26, 2023CVE publishedPublication date reported by the CVE source.
- Nov 8, 2023Exploitation reportedJuniper-confirmed successful exploitation
- Oct 21, 2025Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=21.2 <21.2R3-S8
- Affected versionversion=21.4 <21.4R3-S6
- Affected versionversion=22.1 <22.1R3-S5
- Affected versionversion=22.2 <22.2R3-S3
- Affected versionversion=22.3 <22.3R3-S2
- Affected versionversion=22.4 <22.4R2-S2, 22.4R3
- Affected versionversion=23.2 <23.2R1-S2, 23.2R2
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- watchTowr Juniper pre-authentication RCE chainfunctional · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Reported exploitation
- CISA Known Exploited Vulnerabilities entryknown exploited catalog
- Juniper-confirmed successful exploitationreported exploitation
Technologies
Your stack
See the directory against your own environment.
Your stack
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