CVE-2023-36844
MediumExploitedPublic exploitA PHP External Variable Modification vulnerability in J-Web of Juniper Networks Junos OS on EX Series allows an unauthenticated, network-based attacker to control certain, important environment variables.
Published Aug 18, 2023 · Updated Oct 21, 2025 · Also known as TR-23-0474
Key Facts
Patch immediately- CVE-2023-36844 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 and is known to be used in ransomware campaigns. Public exploit code is available.
- EPSS estimates a 90% probability of exploitation in the next 30 days.
- Fixed versions are available, including Junos 20.4, Junos OS 20.4R3-S9, Junos OS 21.1*.
- 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)
90%
Higher than 99.7% of all scored CVEs
Exploited in the wild
Yes
4 catalog listings, used by ransomware
Public exploit code
Available
Proof-of-concept or weaponized module
Get the full CVE-2023-36844 brief as a PDF
Every affected product and fixed release, exploitation status and a first 24 hours response checklist, emailed within minutes.
Description
A PHP External Variable Modification vulnerability in J-Web of Juniper Networks Junos OS on EX Series allows an unauthenticated, network-based attacker to control certain, important environment variables.
Using a crafted request an attacker is able to modify
certain PHP environment variables leading to partial loss of integrity, which may allow chaining to other vulnerabilities. This issue affects Juniper Networks Junos OS on EX Series:
* All versions prior to 20.4R3-S9; * 21.1 versions 21.1R1 and later; * 21.2 versions prior to 21.2R3-S7; * 21.3 versions
prior to
21.3R3-S5; * 21.4 versions
prior to
21.4R3-S5; * 22.1 versions
prior to
22.1R3-S4; * 22.2 versions
prior to
22.2R3-S2; * 22.3 versions
prior to 22.3R3-S1; * 22.4 versions
prior to
22.4R2-S2, 22.4R3; * 23.2 versions prior to
23.2R1-S1, 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 | Known |
| CIRCL KEV | Oct 14, 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
95 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| JunosJuniper | 20.4, 20.4-r1, 20.4-r1-s1, 20.4-r2, 20.4-r2-s1, 20.4-r2-s2, 20.4-r3, 20.4-r3-s1 | 20.4 |
| Junos OS | >= 21.1 | 20.4R3-S9 |
Patched Releases
Junos
20.4
Junos OS
20.4R3-S9, 21.1*, 21.2R3-S6, 21.3R3-S5, 21.4R3-S5, 22.1R3-S4, 22.2R3-S2, 22.3R3-S1, 22.4R2-S2, 22.4R3, 23.2R1-S1, 23.2R2
Timeline
Publicly disclosed
Aug 18, 2023
Added to Industry KEV feed
Aug 29, 2023
Added to CIRCL KEV
Oct 14, 2023
Added to CISA KEV
Nov 13, 2023
Added to ENISA EUVD
Nov 13, 2023
Last updated
Oct 21, 2025
Weakness Type
- CWE-473 PHP External Variable Modification
References
- advisoryhttps://supportportal.juniper.net/JSA72300
- advisoryhttps://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2023-36844
- advisoryhttps://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2023-36845
- advisoryhttps://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2023-36846
- advisoryhttps://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2023-36847
FAQ
Common Questions.
A PHP External Variable Modification vulnerability in J-Web of Juniper Networks Junos OS on EX Series allows an unauthenticated, network-based attacker to control certain, important environment variables.
Affected: Junos (Juniper) versions 20.4, 20.4-r1, 20.4-r1-s1, 20.4-r2, 20.4-r2-s1, 20.4-r2-s2, 20.4-r3, 20.4-r3-s1; Junos OS versions >= 21.1. 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 and is known to be used in ransomware campaigns.
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 20.4, Junos OS 20.4R3-S9, Junos OS 21.1*.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.
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