CVE-2023-36851
MediumExploitedPublic exploitA Missing Authentication for Critical Function vulnerability in Juniper Networks Junos OS on SRX Series allows an unauthenticated, network-based attacker to cause limited impact to the file system integrity.
Published Sep 27, 2023 · Updated Feb 26, 2026
Key Facts
Patch immediately- CVE-2023-36851 is a medium-severity vulnerability (CVSS 5.3 v3.1) affecting Junos (Juniper), Junos OS.
- It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Aug 29, 2023. Public exploit code is available.
- EPSS estimates a 1.1% probability of exploitation in the next 30 days.
- Fixed versions are available, including Junos OS 21.2R3-S8, Junos OS 21.4R3-S6, Junos OS 22.1R3-S5.
- Brandefense priority: patch immediately, because it is listed as exploited in the wild.
CVSS v3.1
5.3
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
EPSS (30-day exploit likelihood)
1.1%
Higher than 65.6% of all scored CVEs
Exploited in the wild
Yes
4 catalog listings
Public exploit code
Available
Proof-of-concept or weaponized module
Get the full CVE-2023-36851 brief as a PDF
Every affected product and fixed release, exploitation status and a first 24 hours response checklist, emailed within minutes.
Description
A Missing Authentication for Critical Function vulnerability in Juniper Networks Junos OS on SRX Series 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 and download arbitrary files via J-Web, leading to a loss of
integrity or confidentiality, which may allow chaining to other vulnerabilities.
This issue affects Juniper Networks Junos OS on SRX Series:
*
21.2 versions prior to 21.2R3-S8; * 21.4
versions prior to
21.4R3-S6; * 22.1
versions prior to
22.1R3-S5; * 22.2
versions prior to
22.2R3-S3; * 22.3
versions prior to
22.3R3-S2; * 22.4 versions prior to 22,4R2-S2, 22.4R3; * 23.2 versions prior to
23.2R1-S2, 23.2R2.
Known-Exploited Catalog Listings
| Catalog | Added | Remediation due | Ransomware use |
|---|---|---|---|
| CISA KEV | Nov 13, 2023 | Nov 17, 2023 | Not reported |
| Industry KEV feed | Aug 29, 2023 | Nov 17, 2023 | Not reported |
| CIRCL KEV | Nov 13, 2023 | Nov 17, 2023 | Not reported |
| ENISA EUVD | Nov 13, 2023 | n/a | Not reported |
Required action: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
Affected Products
63 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| JunosJuniper | 21.2, 21.2-r1, 21.2-r1-s1, 21.2-r1-s2, 21.2-r2, 21.2-r2-s1, 21.2-r2-s2, 21.2-r3 | n/a |
| Junos OS | >= 21.2 | 21.2R3-S8 |
Patched Releases
Junos OS
21.2R3-S8, 21.4R3-S6, 22.1R3-S5, 22.2R3-S3, 22.3R3-S2, 22.4R2-S2, 22.4R3, 23.2R1-S2, 23.2R2
Timeline
Added to Industry KEV feed
Aug 29, 2023
Publicly disclosed
Sep 27, 2023
Added to CISA KEV
Nov 13, 2023
Added to CIRCL KEV
Nov 13, 2023
Added to ENISA EUVD
Nov 13, 2023
Last updated
Feb 26, 2026
Weakness Type
- CWE-306 Missing Authentication for Critical Function
References
- advisoryhttps://supportportal.juniper.net/JSA72300
- exploitVulnCheck exploitation report
- exploitVulnCheck exploitation report
- exploitVulnCheck exploitation report
- exploitVulnCheck exploitation report
FAQ
Common Questions.
A Missing Authentication for Critical Function vulnerability in Juniper Networks Junos OS on SRX Series allows an unauthenticated, network-based attacker to cause limited impact to the file system integrity.
Affected: Junos (Juniper) versions 21.2, 21.2-r1, 21.2-r1-s1, 21.2-r1-s2, 21.2-r2, 21.2-r2-s1, 21.2-r2-s2, 21.2-r3; Junos OS versions >= 21.2. The full list is in the CVE brief.
It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Aug 29, 2023.
Yes. It was added on Nov 13, 2023 with a federal remediation due date of Nov 17, 2023.
Public exploit code is available.
Fixed versions are available, including Junos OS 21.2R3-S8, Junos OS 21.4R3-S6, Junos OS 22.1R3-S5.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.
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