# CVE-2020-1920: Regular expression denial of service in react-native

> Attackers can cause application crashes or unresponsiveness via ReDoS in the validateBaseUrl function of the React Native library.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/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:** Yes
- **Published:** 1 Jun 2021
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-7f53-fmmv-mfjv

## What is CVE-2020-1920?

CVE-2020-1920 is a high-severity denial of service vulnerability in Facebook react-native, published on 1 Jun 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A regular expression denial of service (ReDoS) vulnerability in the validateBaseUrl function can cause the application to use excessive resources, become unresponsive, or crash. This was introduced in react-native version 0.59.0 and fixed in version 0.64.1.

Weakness: CWE-697 (Incorrect Comparison), CWE-1333 (Inefficient Regular Expression Complexity)

## Which versions are affected by CVE-2020-1920?

4 open source packages ship an affected version, including react-native. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `react-native` | npm | From 0.59.0 | 0.62.3 |
| `react-native` | npm | From 0.59.0 | 0.62.3 |
| `react-native` | npm | From 0.63.0 | 0.64.1 |
| `react-native` | npm | From 0.63.0 | 0.64.1 |

Products: Facebook React-Native.

## How do I fix CVE-2020-1920?

Upgrade react-native to a fixed version for your release line: 0.62.3 or 0.64.1.

## Is CVE-2020-1920 being exploited?

There is no known exploitation of CVE-2020-1920 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-1920 and fix it if it is affected.

What it is: CVE-2020-1920 is a high-severity denial of service vulnerability in Facebook react-native, published on 1 Jun 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-2020-1920 in the wild and no public exploit code.

Affected packages and fixed versions:
- react-native (npm): affected from 0.59.0; fixed in 0.62.3
- react-native (npm): affected from 0.59.0; fixed in 0.62.3
- react-native (npm): affected from 0.63.0; fixed in 0.64.1
- react-native (npm): affected from 0.63.0; fixed in 0.64.1

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-2020-1920/ (Markdown: https://insights.sbomify.com/CVE-2020-1920/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-1920
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-1920
- OSV: https://osv.dev/vulnerability/CVE-2020-1920

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-1920/
Summaries are generated and may contain mistakes; the official description above is the record.