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UK Cyber Defence
VulnerabilityAnalyzed

CVE-2023-36845

Juniper Junos OS EX Series and SRX Series PHP External Variable Modification Vulnerability

KEVCRITICAL 9.8EPSS 95.1%

Does this matter?

Known to be exploited in the wild (CISA KEV, CISA remediation deadline 17 November 2023). Treat as an emergency change: patch or isolate now, then hunt for prior compromise.

Description

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.

CVSS 3.1
9.8 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS
95.07% probability · 100th percentile
Public exploits
None in Exploit-DB
CISA KEV
Listed 13 November 2023 · due 17 November 2023
Weakness
CWE-473
Affected
juniper/junos
Source
sirt@juniper.net
EPSS trend
0%50%100%30 October 2026: 95.07%30 October 202630 October 2026

EPSS 95.1% since 30 October 2026; no change recorded yet. The dashed line is the ten per cent mark our analysts treat as “patch before the next change window”. Points are recorded when the score first appears and whenever it moves by a percentage point or more.

CISA notes

Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable. https://supportportal.juniper.net/s/article/2023-08-Out-of-Cycle-Security-Bulletin-Junos-OS-SRX-Series-and-EX-Series-Multiple-vulnerabilities-in-J-Web-can-be-combined-to-allow-a-preAuth-Remote-Code-Execution?language=en_US ; https://nvd.nist.gov/vuln/detail/CVE-2023-36845

Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.