# CVE-2020-1757: Improper Input Validation in Undertow

> Attackers can bypass security controls in Undertow by exploiting incorrect servlet path normalization involving semicolons.

- **Severity:** High 8.1 (`CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 21 Apr 2020
- **Updated:** 4 Aug 2024
- **Also known as:** DEBIAN-CVE-2020-1757, GHSA-2w73-fqqj-c92p, UBUNTU-CVE-2020-1757

## What is CVE-2020-1757?

CVE-2020-1757 is a high-severity vulnerability in Redhat Jboss Enterprise Application Platform, published on 21 Apr 2020. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

A flaw was found in all undertow-2.x.x SP1 versions prior to undertow-2.0.30.SP1, all undertow-1.x.x and undertow-2.x.x versions prior to undertow-2.1.0.Final, where the Servlet container causes servletPath to normalize incorrectly by truncating the path after semicolon which may lead to an application mapping resulting in the security bypass.

Weakness: CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor), CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2020-1757?

2 open source packages ship an affected version, including io.undertow:undertow-core. It affects 6 products.


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

Products: Redhat Jboss Data Grid, Redhat Jboss Enterprise Application Platform, Redhat Jboss Fuse, Redhat Openshift Application Runtimes, Redhat Single Sign-On, Redhat Undertow.

## How do I fix CVE-2020-1757?

Upgrade io.undertow:undertow-core to 2.1.0 or later.

## Is CVE-2020-1757 being exploited?

There is no known exploitation of CVE-2020-1757 in the wild and no public exploit code.

## Other vulnerabilities in Redhat Jboss Enterprise Application Platform

- [CVE-2019-14887](https://insights.sbomify.com/CVE-2019-14887/): Inadequate Encryption Strength and Algorithm Downgrade in Wildfly (high 7.4)
- [CVE-2020-1710](https://insights.sbomify.com/CVE-2020-1710/): Other in JBoss Enterprise Application Platform (medium 5.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-1757 and fix it if it is affected.

What it is: CVE-2020-1757 is a high-severity vulnerability in Redhat Jboss Enterprise Application Platform, published on 21 Apr 2020. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2020-1757 in the wild and no public exploit code.

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

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-2020-1757/ (Markdown: https://insights.sbomify.com/CVE-2020-1757/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-1757
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-1757
- OSV: https://osv.dev/vulnerability/CVE-2020-1757

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-1757/
Summaries are generated and may contain mistakes; the official description above is the record.