# CVE-2020-26938: oauth2-server through 3.1.1 vulnerable to Open Redirect

> A malicious client can bypass redirect URI validation in node-oauth2-server, potentially enabling XSS or phishing attacks via crafted authorization requests.

- **Severity:** High 7.2 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/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:** No
- **Published:** 29 Aug 2022
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-4rg6-fm25-gc34

## What is CVE-2020-26938?

CVE-2020-26938 is a high-severity vulnerability in n/a, published on 29 Aug 2022. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

In oauth2-server (aka node-oauth2-server) through 3.1.1, the value of the redirect_uri parameter received during the authorization and token request is checked against an incorrect URI pattern ("[a-zA-Z][a-zA-Z0-9+.-]+:") before making a redirection. This allows a malicious client to pass an XSS payload through the redirect_uri parameter while making an authorization request. NOTE: this vulnerability is similar to CVE-2020-7741.

Weakness: CWE-601 (URL Redirection to Untrusted Site)

## Which versions are affected by CVE-2020-26938?

2 open source packages ship an affected version, including oauth2-server. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `oauth2-server` | npm | All versions to 3.1.1 | None |
| `oauth2-server` | npm | All versions to 3.1.1 | None |

Products: Oauth2-Server Project Oauth2-Server.

## How do I fix CVE-2020-26938?

No fix has been published for CVE-2020-26938 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-26938 being exploited?

There is no known exploitation of CVE-2020-26938 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2017-18924](https://insights.sbomify.com/CVE-2017-18924/): Code Injection in oauth2-server (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-26938 and fix it if it is affected.

What it is: CVE-2020-26938 is a high-severity vulnerability in n/a, published on 29 Aug 2022. 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-2020-26938 in the wild and no public exploit code.

Affected packages and fixed versions:
- oauth2-server (npm): affected all versions up to 3.1.1; no fix listed
- oauth2-server (npm): affected all versions up to 3.1.1; no fix listed

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-2020-26938/ (Markdown: https://insights.sbomify.com/CVE-2020-26938/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-26938
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-26938
- OSV: https://osv.dev/vulnerability/CVE-2020-26938

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-26938/
Summaries are generated and may contain mistakes; the official description above is the record.