# CVE-2020-3436: File upload in Cisco Adaptive Security Appliance (ASA) Software

> Unauthenticated remote attackers can upload large files to trigger a watchdog timeout and device reload, causing denial of service.

- **Severity:** High 8.6 (`CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 21 Oct 2020
- **Updated:** 13 Nov 2024
- **Also known as:** GHSA-w8jp-qw34-jrrq

## What is CVE-2020-3436?

CVE-2020-3436 is a high-severity vulnerability in Cisco Adaptive Security Appliance, published on 21 Oct 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A vulnerability in the web services interface of Cisco Adaptive Security Appliance (ASA) and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to upload arbitrary-sized files to specific folders on an affected device, which could lead to an unexpected device reload. The vulnerability exists because the affected software does not efficiently handle the writing of large files to specific folders on the local file system. An attacker could exploit this vulnerability by uploading files to those specific folders. A successful exploit could allow the attacker to write a file that triggers a watchdog timeout, which would cause the device to unexpectedly reload, causing a denial of service (DoS) condition.

Weakness: CWE-434 (Unrestricted Upload of File with Dangerous Type)

## Which versions are affected by CVE-2020-3436?

It affects 3 products.


Products: Cisco Adaptive Security Appliance, Cisco Adaptive Security Appliance Software, Cisco Secure Firewall Threat Defense.

## How do I fix CVE-2020-3436?

No fix has been published for CVE-2020-3436 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-3436 being exploited?

There is no known exploitation of CVE-2020-3436 in the wild and no public exploit code.

## Other vulnerabilities in Cisco Adaptive Security Appliance

- [CVE-2021-1573](https://insights.sbomify.com/CVE-2021-1573/): Denial of service in Cisco Adaptive Security Appliance Software (high 8.6)
- [CVE-2021-34793](https://insights.sbomify.com/CVE-2021-34793/): Denial of service in Cisco Adaptive Security Appliance (ASA) Software (high 8.6)
- [CVE-2021-40117](https://insights.sbomify.com/CVE-2021-40117/): Denial of service in Cisco Adaptive Security Appliance (ASA) Software (high 8.6)
- [CVE-2021-40118](https://insights.sbomify.com/CVE-2021-40118/): Denial of service in Cisco Adaptive Security Appliance (ASA) Software (high 8.6)
- [CVE-2020-3304](https://insights.sbomify.com/CVE-2020-3304/): Denial of service in Cisco Adaptive Security Appliance (ASA) Software (high 8.6)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-3436 and fix it if it is affected.

What it is: CVE-2020-3436 is a high-severity vulnerability in Cisco Adaptive Security Appliance, published on 21 Oct 2020. 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-2020-3436 in the wild and no public exploit code.

Affected product: Cisco Adaptive Security Appliance. 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-2020-3436/ (Markdown: https://insights.sbomify.com/CVE-2020-3436/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-3436
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-3436
- OSV: https://osv.dev/vulnerability/CVE-2020-3436

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-3436/
Summaries are generated and may contain mistakes; the official description above is the record.