Medium 5.3Known exploited (CISA KEV)Published Aug 17, 2023

CVE-2023-36844Junos OS: EX Series: A PHP vulnerability in J-Web allows an unauthenticated attacker to control important environment variables

Updated under an hour ago (2026-10-19 10:10 UTC)

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It affects Juniper Networks Junos OS and 1 other product. Add what you run to find out whether that includes you.

CISA lists it as known exploited since Nov 13, 2023; federal agencies had to remediate by Nov 17, 2023. Treat that date as your deadline.

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Every CVE for Juniper Networks Junos OS

Exploited in the last 30 days

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.

CVSS: 5.3 MEDIUM (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Weakness (CWE): CWE-473
Known exploited: Added to CISA KEV Nov 13, 2023; federal remediation due Nov 17, 2023Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
EPSS (exploitation in the next 30 days): 89.96% (percentile 100)
Assigned by: juniper
NVD analysis: Analyzed
Record last updated: Oct 21, 2025
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Juniper Networks Junos OS juniper_networks:junos_os (from the name)	before 20.4R3-S9; from 21.1 before 21.1*; from 21.2 before 21.2R3-S6; from 21.3 before 21.3R3-S5; from 21.4 before 21.4R3-S5; from 22.1 before 22.1R3-S4; from 22.2 before 22.2R3-S2; from 22.3 before 22.3R3-S1; and 2 more ranges	CNA record
juniper junos juniper:junos	before 20.4; 20.4; 20.4; 20.4; 20.4; 20.4; 20.4; 20.4; and 86 more ranges	NVD

References

https://supportportal.juniper.net/JSA72300vendor-advisory, mitigation
http://packetstormsecurity.com/files/174865/Juniper-SRX-Firewall-EX-Switch-Remote-Code-Execution.htmlexploit, third-party-advisory, vdb-entry
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2023-36844us-government-resource

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.