CVE-2023-36844Junos OS: EX Series: A PHP vulnerability in J-Web allows an unauthenticated attacker to control important environment variables
- 5.3MediumCVSS base score
- 90.0%Exploitation in 30 daysEPSS · top 0.2% of all CVEs
- YesKnown exploitedin CISA's KEV since 13 Nov 2023
- 1Public exploitsMetasploit, Nuclei and Exploit-DB
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.
Exploited in the wild
CISA lists this vulnerability in its Known Exploited Vulnerabilities catalog as Juniper Junos OS EX Series PHP External Variable Modification Vulnerability.
- Added
- 13 Nov 2023
- Fix due (US federal)
- 17 Nov 2023
- Used by ransomware
- Not known
Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
ENISA's EU Vulnerability Database lists it as exploited, from CISA's KEV, since 13 Nov 2023.
Public exploit
An exploit or proof of concept is public: anyone can try it against an unpatched system. The public collections list a Nuclei template for it. CISA's SSVC rates its exploitation: it is being exploited.
Show the exploits1
Nuclei templates1 template
- Juniper Devices - Remote Code Execution (Nuclei template) (opens in a new tab)
http/cves/2023/CVE-2023-36844.yamlSeverity medium
Modules, templates and exploits as listed by the Metasploit Framework (BSD-3-Clause), ProjectDiscovery's Nuclei templates (MIT) and the Exploit Database (GPLv2), read once a day. Where the data comes from
Timeline
ID reserved
By juniper
- 51 days later
· 51 days later
Published
- 3 months later
· 3 months later
Added to CISA KEV
Known exploited in the wild
- 24 months later
· 24 months later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| juniperCNA (assigner) | 3.1 | Medium5.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N |
| NVDNVD · Analyzed | 3.1 | Medium5.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N |
- EPSS (exploitation in 30 days)
- 90.0% · top 0.2% of all CVEs (14 Nov 2026)
- CISA SSVC
- Exploitation: active · Automatable: yes · Technical impact: total
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 5.3.
Affected products
- affected < 20.4R3-S9
- affected 21.1 – < 21.1*
- affected 21.2 – < 21.2R3-S6
- affected 21.3 – < 21.3R3-S5
- affected 21.4 – < 21.4R3-S5
- affected 22.1 – < 22.1R3-S4
- affected 22.2 – < 22.2R3-S2
- affected 22.3 – < 22.3R3-S1
- affected 22.4 – < 22.4R2-S2, 22.4R3
- affected 23.2 – < 23.2R1-S1, 23.2R2
What to do
Solution: The following software releases have been updated to resolve this specific issue: 20.4R3-S9*, 21.2R3-S7*, 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*, 23.4R1*, and all subsequent releases. *Pending Publication
Workaround: Disable J-Web, or limit access to only trusted hosts.
Exploitation: Juniper SIRT is not aware of any malicious exploitation of this vulnerability.
References
References3
- https://supportportal.juniper.net/JSA72300 (opens in a new tab)vendor-advisorymitigationx_transferred
- http://packetstormsecurity.com/files/174865/Juniper-SRX-Firewall-EX-Switch-Remote-Code-Execution.html (opens in a new tab)x_transferred
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2023-36844 (opens in a new tab)government-resource
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- CISA KEV catalog (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2023-40764 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2023-36844)Record last updated .