Known exploited · Juniper
CVE-2023-36851: Juniper Junos OS SRX Series Missing Authentication for Critical Function Vulnerability
What it is
Juniper Junos OS on SRX Series contains a missing authentication for critical function vulnerability that allows an unauthenticated, network-based attacker to cause limited impact to the file system integrity. With a specific request to webauth_operation.php that doesn't require authentication, an attacker is able to upload arbitrary files via J-Web, leading to a loss of integrity for a certain part of the file system, which may allow chaining to other vulnerabilities.
- Vendor
- Juniper
- Product
- Junos OS
- Added to KEV
- November 13, 2023
- CISA due date
- November 17, 2023
- Ransomware use
- Unknown
What CISA requires
Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
Forensic triage
No
What to do now
- Find every instance of Junos OS you run, including the forgotten ones, and check its version against the vendor advisory.
- Apply the vendor's fix or mitigation, before November 17, 2023 if you are bound by CISA's deadline, sooner if it faces the internet.
- Assume it was tried against you already: look for signs of exploitation from the date it was added, not from the day you patched.
References
H2 Security
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Start freeSource: CISA Known Exploited Vulnerabilities Catalog (public domain), catalog version 2026.10.01.