# CVE-2020-16904: Azure Functions Elevation of Privilege Vulnerability

> An unauthenticated attacker can bypass access key validation to invoke HTTP Functions, leading to privilege escalation.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N/E:P/RL:O/RC:C`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 16 Oct 2020
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-v3gf-q256-843h

## What is CVE-2020-16904?

CVE-2020-16904 is a medium-severity authentication bypass vulnerability in Microsoft Azure Functions, published on 16 Oct 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

<p>An elevation of privilege vulnerability exists in the way Azure Functions validate access keys.</p>
<p>An unauthenticated attacker who successfully exploited this vulnerability could invoke an HTTP Function without proper authorization.</p>
<p>This security update addresses the vulnerability by correctly validating access keys used to access HTTP Functions.</p>

Weakness: CWE-863 (Incorrect Authorization)

## Which versions are affected by CVE-2020-16904?

It affects 1 product.


Products: Microsoft Azure Functions.

## How do I fix CVE-2020-16904?

No fix has been published for CVE-2020-16904 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-16904 being exploited?

There is no known exploitation of CVE-2020-16904 in the wild and no public exploit code.

## Other vulnerabilities in Microsoft Azure Functions

- [CVE-2026-21532](https://insights.sbomify.com/CVE-2026-21532/): Azure Function Information Disclosure Vulnerability (high 8.2)
- [CVE-2024-49052](https://insights.sbomify.com/CVE-2024-49052/): Microsoft Azure PolicyWatch Elevation of Privilege Vulnerability (high 8.2)
- [CVE-2025-33074](https://insights.sbomify.com/CVE-2025-33074/): Azure Functions Remote Code Execution Vulnerability (high 7.5)
- [CVE-2024-38204](https://insights.sbomify.com/CVE-2024-38204/): Imagine Cup site Information Disclosure Vulnerability (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-16904 and fix it if it is affected.

What it is: CVE-2020-16904 is a medium-severity authentication bypass vulnerability in Microsoft Azure Functions, published on 16 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-2020-16904 in the wild and no public exploit code.

Affected product: Microsoft Azure Functions. 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-2020-16904/ (Markdown: https://insights.sbomify.com/CVE-2020-16904/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-16904
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-16904
- OSV: https://osv.dev/vulnerability/CVE-2020-16904

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From sbomify Insights: https://insights.sbomify.com/CVE-2020-16904/
Summaries are generated and may contain mistakes; the official description above is the record.