# CVE-2021-20220: HTTP request smuggling in Undertow

> Attackers can exploit HTTP request smuggling in Undertow to poison caches, perform XSS, or access sensitive data from other users' requests.

- **Severity:** Medium 4.8 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 23 Feb 2021
- **Updated:** 3 Aug 2024
- **Also known as:** DEBIAN-CVE-2021-20220, GHSA-qjwc-v72v-fq6r, UBUNTU-CVE-2021-20220

## What is CVE-2021-20220?

CVE-2021-20220 is a medium-severity vulnerability in Netapp Active Iq Unified Manager, published on 23 Feb 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A flaw was found in Undertow. A regression in the fix for CVE-2020-10687 was found. HTTP request smuggling related to CVE-2017-2666 is possible against HTTP/1.x and HTTP/2 due to permitting invalid characters in an HTTP request. This flaw allows an attacker to poison a web-cache, perform an XSS attack, or obtain sensitive information from request other than their own. The highest threat from this vulnerability is to data confidentiality and integrity.

Weakness: CWE-444 (Inconsistent Interpretation of HTTP Requests)

## Which versions are affected by CVE-2021-20220?

4 open source packages ship an affected version, including io.undertow:undertow-core. It affects 3 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `io.undertow:undertow-core` | Maven | All versions | 2.0.34 |
| `io.undertow:undertow-core` | Maven | All versions | 2.0.34 |
| `io.undertow:undertow-core` | Maven | From 2.1.0 | 2.1.6 |
| `io.undertow:undertow-core` | Maven | From 2.1.0 | 2.1.6 |

Products: Netapp Active Iq Unified Manager, Netapp Oncommand Workflow Automation, Redhat Undertow.

## How do I fix CVE-2021-20220?

Upgrade io.undertow:undertow-core to a fixed version for your release line: 2.0.34 or 2.1.6.

## Is CVE-2021-20220 being exploited?

There is no known exploitation of CVE-2021-20220 in the wild and no public exploit code.

## Other vulnerabilities in Netapp Active Iq Unified Manager

- [CVE-2022-31692](https://insights.sbomify.com/CVE-2022-31692/): Spring Security authorization rules can be bypassed via forward or include dispatcher types (critical 9.8)
- [CVE-2022-2526](https://insights.sbomify.com/CVE-2022-2526/): Use after free in systemd-resolved (critical 9.8)
- [CVE-2022-22978](https://insights.sbomify.com/CVE-2022-22978/): Authorization bypass in Spring Security (critical 9.8)
- [CVE-2021-22931](https://insights.sbomify.com/CVE-2021-22931/): Code injection in Node (critical 9.8)
- [CVE-2018-2938](https://insights.sbomify.com/CVE-2018-2938/): Code injection in Java (critical 9.0)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-20220 and fix it if it is affected.

What it is: CVE-2021-20220 is a medium-severity vulnerability in Netapp Active Iq Unified Manager, published on 23 Feb 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-2021-20220 in the wild and no public exploit code.

Affected packages and fixed versions:
- io.undertow:undertow-core (Maven): affected all versions; fixed in 2.0.34
- io.undertow:undertow-core (Maven): affected all versions; fixed in 2.0.34
- io.undertow:undertow-core (Maven): affected from 2.1.0; fixed in 2.1.6
- io.undertow:undertow-core (Maven): affected from 2.1.0; fixed in 2.1.6

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-2021-20220/ (Markdown: https://insights.sbomify.com/CVE-2021-20220/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-20220
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-20220
- OSV: https://osv.dev/vulnerability/CVE-2021-20220

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-20220/
Summaries are generated and may contain mistakes; the official description above is the record.