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Juniper · Junos OS

CVE-2023-36845

Junos OS: EX and SRX Series: A PHP vulnerability in J-Web allows an unauthenticated to control an important environment variable

Exploited in attacks Critical 9.8 Attack chance: 95%
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What it is

A PHP External Variable Modification vulnerability in J-Web of Juniper Networks Junos OS on EX Series

and SRX Series

allows an unauthenticated, network-based attacker to remotely execute code.

Using a crafted request which sets the variable PHPRC an attacker is able to modify the PHP execution environment allowing the injection und execution of code.


This issue affects Juniper Networks Junos OS on EX Series


and


SRX 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

22.3R2-S2, 22.3R3-S1;
* 22.4 versions

prior to

22.4R2-S1, 22.4R3;
* 23.2 versions prior to 23.2R1-S1, 23.2R2.

CISA: Juniper Junos OS on EX Series and SRX Series contains a PHP external variable modification vulnerability that allows an unauthenticated, network-based attacker to control an important environment variable. Using a crafted request, which sets the variable PHPRC, an attacker is able to modify the PHP execution environment allowing the injection und execution of code.

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
Critical 9.8 CVSS 3.1
Chance of attacks in the next 30 days (EPSS)
95% in the top 0.1% of all known vulnerabilities
Weakness
CWE-473
More details
NVD · CVE.org · CISA
All references (3)

More exploited flaws from Juniper

AddedVulnerabilityProductSeverityAttack chance
Mar 13, 2025Improper Isolation or CompartmentalizationCVE-2025-21590Junos OSMedium 6.71.7%
Nov 13, 2023EX Series PHP External Variable ModificationCVE-2023-36844Junos OSMedium 5.390%
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.