# CVE-2023-27997: Fortinet FortiOS and FortiProxy SSL-VPN Heap-Based Buffer Overflow

> Remote attackers can execute arbitrary code via crafted requests exploiting a heap-based buffer overflow in Fortinet SSL-VPN.

- **Severity:** Critical 9.2 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:F/RL:X/RC:R`)
- **Exploited in the wild:** Yes, since 13 Jun 2023 (CISA KEV), used in ransomware
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 13 Jun 2023
- **Updated:** 31 Jul 2026
- **Also known as:** GHSA-2hj2-fcr9-9p35

## What is CVE-2023-27997?

CVE-2023-27997 is a critical memory corruption vulnerability in Fortinet Fortios, published on 13 Jun 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A heap-based buffer overflow vulnerability [CWE-122] in FortiOS version 7.2.4 and below, version 7.0.11 and below, version 6.4.12 and below, version 6.0.16 and below and FortiProxy version 7.2.3 and below, version 7.0.9 and below, version 2.0.12 and below, version 1.2 all versions, version 1.1 all versions SSL-VPN may allow a remote attacker to execute arbitrary code or commands via specifically crafted requests.

Weakness: CWE-787 (Out-of-bounds Write), CWE-122 (Heap-based Buffer Overflow)

## Which versions are affected by CVE-2023-27997?

It affects 2 products.


Products: Fortinet Fortios, Fortinet Fortiproxy.

## How do I fix CVE-2023-27997?

No fix has been published for CVE-2023-27997 yet. Limit exposure of the affected software until one is available. US federal agencies must fix it by 4 Jul 2023.

## Is CVE-2023-27997 being exploited?

Yes. Attackers have exploited CVE-2023-27997 in the wild since at least 13 Jun 2023, including in ransomware campaigns.

Public exploit code:

- Safely detect whether a FortiGate SSL VPN instance is vulnerable to CVE-2023-27997 based on response timing (github_poc): https://github.com/BishopFox/CVE-2023-27997-check
- xortigate-cve-2023-27997 (github_poc): https://github.com/lexfo/xortigate-cve-2023-27997
- POC FortiOS SSL-VPN buffer overflow vulnerability (github_poc): https://github.com/rio128128/CVE-2023-27997-POC
- https://github.com/delsploit/CVE-2023-27997 (github_poc): https://github.com/delsploit/CVE-2023-27997
- Search vulnerable FortiOS devices via Shodan (CVE-2023-27997) (github_poc): https://github.com/TechinsightsPro/ShodanFortiOS
- VampSecure Labs: FortiOS CVE scanner (CVE-2018-13379, CVE-2022-40684, CVE-2023-27997, CVE-2024-21762) (github_poc): https://github.com/Vampsecure-Labs/vamp-forticheck

## Other vulnerabilities in Fortinet Fortios

- [CVE-2024-23113](https://insights.sbomify.com/CVE-2024-23113/): Fortinet Multiple Products Format String (critical 9.8, exploited in the wild)
- [CVE-2022-40684](https://insights.sbomify.com/CVE-2022-40684/): Fortinet Multiple Products Authentication Bypass (critical 9.8, exploited in the wild)
- [CVE-2024-55591](https://insights.sbomify.com/CVE-2024-55591/): Fortinet FortiOS and FortiProxy Authentication Bypass (critical 9.6, exploited in the wild)
- [CVE-2024-21762](https://insights.sbomify.com/CVE-2024-21762/): Fortinet FortiOS Out-of-Bound Write (critical 9.6, exploited in the wild)
- [CVE-2022-42475](https://insights.sbomify.com/CVE-2022-42475/): Fortinet FortiOS Heap-Based Buffer Overflow (critical 9.3, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-27997 and fix it if it is affected.

What it is: CVE-2023-27997 is a critical memory corruption vulnerability in Fortinet Fortios, published on 13 Jun 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: Yes. Attackers have exploited CVE-2023-27997 in the wild since at least 13 Jun 2023, including in ransomware campaigns.

Affected product: Fortinet Fortios. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2023-27997/ (Markdown: https://insights.sbomify.com/CVE-2023-27997/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-27997
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-27997
- OSV: https://osv.dev/vulnerability/CVE-2023-27997

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-27997/
Summaries are generated and may contain mistakes; the official description above is the record.