# CVE-2022-26122: Security feature bypass in Fortinet AV Engine, FortiMail, FortiOS, FortiClient

> Attackers can bypass antivirus detection by manipulating MIME attachments with junk characters in base64 encoding.

- **Severity:** Medium 4.7 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N/E:P/RL:U/RC:R`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 2 Nov 2022
- **Updated:** 22 Oct 2024
- **Also known as:** GHSA-8xr5-vrfj-p7x2

## What is CVE-2022-26122?

CVE-2022-26122 is a medium-severity vulnerability in Fortinet Fortios, published on 2 Nov 2022. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

An insufficient verification of data authenticity vulnerability [CWE-345] in FortiClient, FortiMail and FortiOS AV engines version 6.2.168 and below and version 6.4.274 and below may allow an attacker to bypass the AV engine via manipulating MIME attachment with junk and pad characters in base64.

Weakness: CWE-345 (Insufficient Verification of Data Authenticity)

## Which versions are affected by CVE-2022-26122?

It affects 3 products.


Products: Fortinet Antivirus Engine, Fortinet Fortimail, Fortinet Fortios.

## How do I fix CVE-2022-26122?

No fix has been published for CVE-2022-26122 yet. Limit exposure of the affected software until one is available.

## Is CVE-2022-26122 being exploited?

There is no known exploitation of CVE-2022-26122 in the wild and no public exploit code.

## Other vulnerabilities in Fortinet Fortios

- [CVE-2020-9295](https://insights.sbomify.com/CVE-2020-9295/): Security feature bypass in FortiClientWindows (medium 4.7)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2022-26122 and fix it if it is affected.

What it is: CVE-2022-26122 is a medium-severity vulnerability in Fortinet Fortios, published on 2 Nov 2022. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2022-26122 in the wild and no public exploit code.

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-2022-26122/ (Markdown: https://insights.sbomify.com/CVE-2022-26122/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2022-26122
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2022-26122
- OSV: https://osv.dev/vulnerability/CVE-2022-26122

---
From sbomify Insights: https://insights.sbomify.com/CVE-2022-26122/
Summaries are generated and may contain mistakes; the official description above is the record.