How severe is CVE-2023-36844?

CVE-2023-36844 has a CVSS score of 5.3/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which products are affected by CVE-2023-36844?

Affected package information for CVE-2023-36844 is not yet fully mapped. Check the official advisory links for details.

How do I patch CVE-2023-36844?

Apply the juniper junos security patch or hotfix for CVE-2023-36844 on the affected version, following the vendor advisory for your exact build.

How do I detect CVE-2023-36844 across my infrastructure?

Inventory every juniper junos deployment and check each version against the affected-products list above. Because the exploit targets the running system rather than your application code, also watch for exploitation at the network and runtime layer — O3 flags the exploit behaviour from runtime telemetry and egress traffic even before a vulnerable build is confirmed.

How do I mitigate CVE-2023-36844 if there is no patch (or I can't update yet)?

Cut exposure now: restrict the management/admin interface to trusted networks, segment the device, and apply the vendor's recommended configuration mitigations and any WAF/IPS signature. O3's runtime protection blocks the exploit chain at execution, holding the line on unpatched or end-of-life systems until you can patch.

How does O3 Security protect against CVE-2023-36844?

O3 detects and blocks CVE-2023-36844 exploitation at runtime: eBPF exploit-chain detection, plus L7 egress monitoring that catches the post-exploitation callback and severs the attacker's outbound channel.

Is CVE-2023-36844 actively exploited in the wild?

Yes. There are 7 known exploit references for CVE-2023-36844, including 5 in-the-wild exploitations observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2023-36844?

CVE-2023-36844 has an EPSS (Exploit Prediction Scoring System) score of 91.0%, placing it in the 100th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. A score above 50% indicates significantly elevated exploitation risk — immediate patching is strongly recommended.

Is CVE-2023-36844 in the CISA Known Exploited Vulnerabilities catalog?

Yes. CVE-2023-36844 (Juniper Junos OS EX Series PHP External Variable Modification Vulnerability) was added to CISA's Known Exploited Vulnerabilities (KEV) catalog on 2023-11-13. CISA required all US federal civilian agencies to remediate this vulnerability by 2023-11-17. The required action was: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable. Being listed in the KEV catalog is the strongest possible confirmation of active exploitation — treat this as a critical priority.

What type of vulnerability is CVE-2023-36844?

CVE-2023-36844 is classified as CWE-473 (CWE-473). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

Which products and versions are affected by CVE-2023-36844?

CVE-2023-36844 affects juniper junos (10 versions, e.g. 20.4, 21.1, 21.2…). Check the affected-products list on this page against your deployed version to confirm exposure.

Is there exploit tooling available for CVE-2023-36844?

A Nuclei detection template exists for CVE-2023-36844, meaning automated scanners can fingerprint it. A Metasploit module references CVE-2023-36844, which lowers the barrier to weaponization. Public exploit tooling significantly increases real-world risk — prioritize patching and ensure detection coverage. Exploit tooling should only ever be used in isolated, authorized testing environments.

When was CVE-2023-36844 published, and has it been updated?

CVE-2023-36844 was published on August 17, 2023 and was last updated on June 17, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

CISA KEV·Added 2023-11-13 — agencies required to remediate by 2023-11-17

CVE-2023-36844

MEDIUM

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…

Published

Aug 17, 2023

Updated

Jun 17, 2026

Affected

0 pkgs

Patched

None yet

Exploits

7 known

EPSS Exploitation Probability

via FIRST.org ↗

91.0%probability of exploitation in next 30 days

Very High Risk100th percentile+1.34%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Description

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.

Affected Products

1 product · 94 configurations

junosjuniper

< 20.4

10 versions

20.421.121.221.321.422.122.222.322.423.2

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.