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

- Exploited (CISA KEV): yes, added 2023-11-13
- Published: 2023-08-17
- CVSS: 5.3 MEDIUM (v3.1)
- EPSS: 90.0% (100th percentile)
- CWE: CWE-473

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.

## Edge WAF coverage (claimed by vendors, not measured)

| Vendor | Status | First rule | Days after publication |
|---|---|---|---|
| Cloudflare | Before feed history | — | — |
| AWS | No public claim | — | — |
| Microsoft Azure | No public claim | — | — |
| Google Cloud | Before feed history | — | — |
| Fastly | Before feed history | — | — |
| F5 | No public claim | — | — |
| Akamai | No public source | — | — |
| OWASP CRS | No public claim | — | — |

## Our test (measured)

- OWASP Core Rule Set 4.25.0, paranoia level 1, anomaly threshold 5, default CRS settings: blocked (3 of 3 requests blocked), template CVE-2023-36844, 2026-11-02
- OWASP Core Rule Set 4.25.0, paranoia level 2, anomaly threshold 5, default CRS settings: blocked (3 of 3 requests blocked), template CVE-2023-36844, 2026-11-02

"No public claim" means no vendor statement names this CVE; "Before feed history" means the CVE is older than the vendor feed. In both cases generic rules may still block it.

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