# CVE-2021-26090: Denial of service in Fortinet FortiMail

> Unauthenticated remote attackers can exhaust memory in FortiMail Webmail via crafted login requests, causing denial of service.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 12 Jul 2021
- **Updated:** 25 Oct 2024
- **Also known as:** GHSA-j48p-m2m2-h4m7

## What is CVE-2021-26090?

CVE-2021-26090 is a medium-severity denial of service vulnerability in Fortinet FortiMail, published on 12 Jul 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A missing release of memory after its effective lifetime vulnerability in the Webmail of FortiMail 6.4.0 through 6.4.4 and 6.2.0 through 6.2.6 may allow an unauthenticated remote attacker to exhaust available memory via specifically crafted login requests.

Weakness: CWE-401 (Missing Release of Memory after Effective Lifetime)

## Which versions are affected by CVE-2021-26090?

It affects 1 product.


Products: Fortinet Fortimail.

## How do I fix CVE-2021-26090?

No fix has been published for CVE-2021-26090 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-26090 being exploited?

There is no known exploitation of CVE-2021-26090 in the wild and no public exploit code.

## Other vulnerabilities in Fortinet FortiMail

- [CVE-2026-104286](https://insights.sbomify.com/CVE-2026-104286/): Fortinet FortiMail Path Traversal (critical 9.8, exploited in the wild)
- [CVE-2021-36166](https://insights.sbomify.com/CVE-2021-36166/): Auth bypass in Fortinet FortiMail (critical 9.8)
- [CVE-2021-24007](https://insights.sbomify.com/CVE-2021-24007/): SQL injection in Fortinet FortiMail (critical 9.8)
- [CVE-2020-9294](https://insights.sbomify.com/CVE-2020-9294/): Auth bypass in FortiMail (critical 9.8)
- [CVE-2023-47539](https://insights.sbomify.com/CVE-2023-47539/): Auth bypass in FortiMail (critical 9.0)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-26090 and fix it if it is affected.

What it is: CVE-2021-26090 is a medium-severity denial of service vulnerability in Fortinet FortiMail, published on 12 Jul 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-26090 in the wild and no public exploit code.

Affected product: Fortinet FortiMail. 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-2021-26090/ (Markdown: https://insights.sbomify.com/CVE-2021-26090/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-26090
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-26090
- OSV: https://osv.dev/vulnerability/CVE-2021-26090

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-26090/
Summaries are generated and may contain mistakes; the official description above is the record.