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Fencer Vulns
medium 5.3

CVE-2023-36844 kev in the critical feed json

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

published 2023-08-17 3 y ago modified 2026-06-17 4 mo ago also EUVD-2023-40764

cvss
5.3
version 3.1, CNA
cisa kev
Exploited
added 2023-11-13
epss
90.0%
EPSS 90.0% chance of exploitation in 30 days, percentile 99.7%
public exploits
1
Metasploit, plus a Nuclei check

Summary

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.

Patch / fix

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

  • Juniper Networks Junos OS 20.4R3-S9, 21.2R3-S6, 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

Timeline

  1. First public exploit (Metasploit exploit/freebsd/http/junos_phprc_auto_prepend_file)
  2. Published
  3. Added to CISA KEV
  4. CISA SSVC: exploitation active
  5. CISA patch deadline

Known exploited

Added
2 y ago
Patch by
2023-11-17 (2 y ago)
Ransomware
Not known
Required action
Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
Vendor, product
Juniper, Junos OS
CISA name
Juniper Junos OS EX Series PHP External Variable Modification Vulnerability

ATT&CK techniques

How it is exploited and what it leads to, in MITRE ATT&CK terms.

  • T1203 Exploitation for Client Execution exploitation
  • T1190 Exploit Public-Facing Application primary impact

kev release 2025-07-28, att&ck v16.1. KEV to ATT&CK mappings by the MITRE Center for Threat-Informed Defense (Mappings Explorer, Apache-2.0). © 2026 The MITRE Corporation. This work is reproduced and distributed with the permission of The MITRE Corporation. Terms of use

CISA SSVC

Exploitation
Active, exploited in the wild
Automatable
yes
Technical impact
total
Assessed
2 y ago

Exploit prediction

89.96% chance of exploitation in the next 30 days, higher than 99.7% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

CVSS scores

assigned by version score vector
CNA 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
NVD 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Affected products

  • Juniper Networks Junos OS

Classification

Weakness
  • CWE-473 PHP External Variable Modification

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.