CISA KEV Medium exploit reference

CVE-2023-36844 — Juniper Junos OS EX Series PHP External Variable Modification Vulnerability

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.

Published Aug 17, 2023 · Updated Oct 13, 2026 · Sources: CISA Known Exploited Vulnerabilities, CVE Program (cve.org) e CISA ADP, NIST National Vulnerability Database, GitHub Security Advisories · CNA: juniper

High

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

CISA KEV · Nov 13, 2023 Detection templates (Nuclei) · 1 Proofs of concept on GitHub · 3

How the score was calculated

Confirmed exploitation (CISA KEV)+35
Public exploit/PoC (nuclei, github)+10
EPSS 90% (30-day exploitation probability)+15
Technical severity (medium)+3
Automatable exploitation (SSVC)+3

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Confirmed

CISA KEV, listed Nov 13, 2023

EPSS FIRST

89.96%

ahead of 100% of scored CVEs · Oct 14, 2026

Affects

Juniper Networks

Junos and 1 more

CVSS base

5.3

Medium · 4 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation

Active

none · proof-of-concept · active

Automatable

Yes

can an attacker script the kill-chain steps

Technical impact

Total

partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

CISA required action CISA

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

US federal deadline: Nov 17, 2023 — passed 1063 day(s) ago

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (Juniper Networks Junos, Juniper Networks Junos OS).
Treat as emergency remediation: the CVE is in CISA KEV (confirmed exploitation).
The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
No fix documented in the sources: reduce exposure and monitor the vendor advisory.
EPSS ahead of 100% of scored CVEs: prioritize it in the patch queue.
Search available logs for exploit probes, errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Juniper Networks	Junos	< 20.4version 20.4version 20.4-r1version 20.4-r1-s1version 20.4-r2version 20.4-r2-s1version 20.4-r2-s2version 20.4-r3 and 86 more version 20.4-r3-s1version 20.4-r3-s2version 20.4-r3-s3version 20.4-r3-s4version 20.4-r3-s5version 20.4-r3-s6version 20.4-r3-s7version 20.4-r3-s8version 21.1-r1version 21.1-r1-s1version 21.1-r2version 21.1-r2-s1version 21.1-r2-s2version 21.1-r3version 21.1-r3-s1version 21.1-r3-s2version 21.1-r3-s3version 21.1-r3-s4version 21.1-r3-s5version 21.2version 21.2-r1version 21.2-r1-s1version 21.2-r1-s2version 21.2-r2version 21.2-r2-s1version 21.2-r2-s2version 21.2-r3version 21.2-r3-s1version 21.2-r3-s2version 21.2-r3-s3version 21.2-r3-s4version 21.2-r3-s5version 21.2-r3-s6version 21.3version 21.3-r1version 21.3-r1-s1version 21.3-r1-s2version 21.3-r2version 21.3-r2-s1version 21.3-r2-s2version 21.3-r3version 21.3-r3-s1version 21.3-r3-s2version 21.3-r3-s3version 21.3-r3-s4version 21.4version 21.4-r1version 21.4-r1-s1version 21.4-r1-s2version 21.4-r2version 21.4-r2-s1version 21.4-r2-s2version 21.4-r3version 21.4-r3-s1version 21.4-r3-s2version 21.4-r3-s3version 21.4-r3-s4version 22.1-r1version 22.1-r1-s1version 22.1-r1-s2version 22.1-r2version 22.1-r2-s1version 22.1-r2-s2version 22.1-r3version 22.1-r3-s1version 22.1-r3-s2version 22.1-r3-s3version 22.2-r1version 22.2-r1-s1version 22.2-r1-s2version 22.2-r2version 22.2-r2-s1version 22.2-r2-s2version 22.2-r3version 22.2-r3-s1version 22.3-r1version 22.3-r1-s1version 22.3-r1-s2version 22.3-r2version 22.3-r2-s1version 22.3-r3version 22.4-r1version 22.4-r1-s1version 22.4-r1-s2version 22.4-r2version 23.2-r1	Vulnerable	NIST National Vulnerability Database
Juniper Networks	Junos OS	< 20.4R3-S9≥ 21.1 and < 21.1*≥ 21.2 and < 21.2R3-S6≥ 21.3 and < 21.3R3-S5≥ 21.4 and < 21.4R3-S5≥ 22.1 and < 22.1R3-S4≥ 22.2 and < 22.2R3-S2≥ 22.3 and < 22.3R3-S1 and 2 more ≥ 22.4 and < 22.4R2-S2, 22.4R3≥ 23.2 and < 23.2R1-S1, 23.2R2	Vulnerable	CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Network

Attack complexity

Low

Privileges required

None

User interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

Low

Availability

None

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Scored by
5.3	CVSS 3.1	Medium	3.9	1.4	sirt@juniper.net via NIST National Vulnerability Database
5.3	CVSS 3.1	Medium	3.9	1.4	nvd@nist.gov via NIST National Vulnerability Database
5.3	CVSS 3.1	Medium	—	—	GitHub, Inc. via GitHub Security Advisories
5.3	CVSS 3.1	Medium	—	—	juniper via CVE Program (cve.org) e CISA ADP

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N (score shown at the top: nvd@nist.gov)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-473

Other CVEs with this weakness →

CISA KEV details CISA

CISA lists a CVE once it has evidence of exploitation against real targets.

Listed

Nov 13, 2023

Federal deadline

Nov 17, 2023

passed 1063 day(s) ago

Ransomware use

Unknown

CISA records ransomware use only for campaigns it has confirmed, so “Unknown” means unrecorded, not ruled out. The deadline binds US federal agencies; for everyone else it is a reference date.

Public exploits, PoCs and detection templates

Public code that demonstrates or tests the flaw raises the odds of mass exploitation — and Nuclei templates help find vulnerable assets in your environment.

Detection templates (Nuclei)

Juniper Devices - Remote Code Execution

Proofs of concept on GitHub

watchtowrlabs/juniper-rce_cve-2023-36844 ★ 114 Aug 25, 2023
A Proof of Concept for chaining the CVEs [CVE-2023-36844, CVE-2023-36845, CVE-2023-36846, CVE-2023-36847] to achieve Remote Code Execution (phpinfo) in Juniper JunOS within SRX and EX Series products.Modified from original exploit developed by @watchTowr . ★ 5 Sep 24, 2023
Perform With Massive Juniper Remote Code Execution ★ 0 Sep 20, 2023

Warning: public PoCs are sometimes disguised malware. Use them only for authorized testing in an isolated environment. This portal does not host exploit code — it only points to the sources.

EPSS over time FIRST

Oct 12, 2026 → Oct 14, 2026 · 3 reading(s) · max 89.96%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
Hunt retroactively in logs from before Nov 13, 2023 (KEV listing): exploitation may have started earlier.

web/proxy/WAF logsnetwork IDS/IPS

Timeline

What happened to this CVE, newest first.

2026
Affected products added · juniper/junos
Oct 13, 2026 · NIST National Vulnerability Database
Source status changed · Published → Analyzed
Oct 13, 2026 · NIST National Vulnerability Database
Record published
Oct 13, 2026
Affected products added · juniper networks/junos os
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
CVSS changed · 5.3
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
Source status changed · → Published
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
SSVC assessment updated
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
Added to CISA KEV (detected)
Oct 13, 2026 · CISA Known Exploited Vulnerabilities
Record created in this database
Oct 13, 2026 · CISA Known Exploited Vulnerabilities
2023
Added to CISA KEV catalog
Nov 12, 2023 · CISA
CVE published
Aug 17, 2023 · juniper

Source activity

Repeated readings are counted rather than listed.

3× References added · Oct 13, 2026 – Oct 13, 2026
1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

6 on the record

supportportal.juniper.net/JSA72300
vendor-advisory, mitigation, Vendor Advisory, CVE Program (cve.org) e CISA ADP
www.cisa.gov/known-exploited-vulnerabilities-catalog
US Government Resource, NIST National Vulnerability Database
nvd.nist.gov/vuln/detail/CVE-2023-36844
GitHub Security Advisories
github.com/advisories/GHSA-f2v8-3pfh-v3xm
GitHub Security Advisories
packetstormsecurity.com/files/174397/Juniper-JunOS-SRX-EX-Remote-Code-Execution.html
GitHub Security Advisories
packetstormsecurity.com/files/174865/Juniper-SRX-Firewall-EX-Switch-Remote-Code-Execution.htm
Exploit, Third Party Advisory, VDB Entry, CVE Program (cve.org) e CISA ADP

Elsewhere on this site

Juniper Networks
every CVE for this vendor

2023-11
what else CISA listed that month

CWE-473
other pages naming this weakness

Related CVEs (same products)

High CVE-2026-102077 Junos OS: MX Series with SPC3: In a source NAT scenario malformed packets will lead to resource leaks and eventually traffic stops 1d
Critical CVE-2026-101982 Junos OS and Junos OS Evolved: A EVPN peer causes an rpd crash or root-level compromise when EVPN-VPWS is used 1d
Critical CVE-2026-101983 Junos OS and Junos OS Evolved: An attacker causes remote code execution when J-Web virtual-domain is configured 1d
Medium CVE-2026-101972 Junos OS and Junos OS Evolved: Malformed OSPF packets causes routing disruption when OSPF is enabled 1d
Medium CVE-2026-101975 Junos OS and Junos OS Evolved: Improper OSPF LSA validation causes an rpd crash when prefix-SID best-route installation is used 1d
Medium CVE-2026-101964 Junos OS and Junos OS Evolved: An attacker can cause an rpd crash via a crafted LDP message 1d

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No fixed version, patch or mitigation documented.
No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2023-36844 is "Juniper Junos OS EX Series PHP External Variable Modification Vulnerability", rated Medium. It affects Junos (Juniper Networks); versions are in the scope table. It is in CISA KEV: there is evidence of real-world exploitation. CVSS 5.3 describes technical severity. EPSS 89.96% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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