BLACKOUT MAP

Juniper · Junos OS

CVE-2023-36844

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

Exploited in attacks Medium 5.3 Attack chance: 90%
Share

What it is

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.

CISA: Juniper Junos OS on EX Series contains a PHP external variable modification vulnerability that 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.

What to do

Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

Deadline for US federal agencies: November 17, 2023

Added to the CISA list
November 13, 2023
Published
August 17, 2023
Severity
Medium 5.3 CVSS 3.1
Chance of attacks in the next 30 days (EPSS)
90% in the top 0.2% of all known vulnerabilities
Weakness
CWE-473
More details
NVD · CVE.org · CISA
All references (2)

More exploited flaws from Juniper

AddedVulnerabilityProductSeverityAttack chance
Mar 13, 2025Improper Isolation or CompartmentalizationCVE-2025-21590Junos OSMedium 6.71.7%
Nov 13, 2023EX Series and SRX Series PHP External Variable ModificationCVE-2023-36845Junos OSCritical 9.895%
Nov 13, 2023SRX Series Missing Authentication for Critical FunctionCVE-2023-36846Junos OSMedium 5.393%
Nov 13, 2023EX Series Missing Authentication for Critical FunctionCVE-2023-36847Junos OSMedium 5.383%
Nov 13, 2023SRX Series Missing Authentication for Critical FunctionCVE-2023-36851Junos OSMedium 5.31.1%
Mar 25, 2022Path TraversalCVE-2020-1631Junos OSHigh 8.84.9%
Oct 2, 2025Improper AuthenticationCVE-2015-7755ScreenOSCritical 9.861%

All of them →

Sources: Known Exploited Vulnerabilities (CISA, public domain), CVE records (cve.org) and EPSS (FIRST). The chance of attacks is the EPSS estimate that someone will try to exploit the flaw in the next 30 days.