## TL;DR

Set NANGO_HMAC_REQUIRED=true, NANGO_HMAC_ALGORITHM=sha256, and NANGO_HMAC_KEY to a secret server-side, then pass the digest in nango.auth with an hmac option. We should have a mechanism to verify the connection ID to avoid malicious attempts to store credentials for another user in the application.

## Steps

1. Issue NangoHQ/nango#582 (closed, 6 comments): Raised by this community [message](https://nango-community.slack.com/archives/C04ABR352H0/p1682327350087349) (and a couple other ones before). We should have a mechanism to verify the connection ID to avoid malicious attempts to store credentials for another user in the application.

2. [bastienbeurier (member)]: To stop attackers spoofing user accounts during OAuth, Nango added HMAC verification. Set NANGO_HMAC_REQUIRED=true, NANGO_HMAC_ALGORITHM=sha256, and NANGO_HMAC_KEY to a secret server-side, then pass the digest in nango.auth with an hmac option. Resolved by PR #591.

## When to use

You are seeing this: Issue NangoHQ/nango#582 (closed, 6 comments): Raised by this community message (and a couple other ones before). Use this skill when you run into "Verify the connection ID to avoid malicious attempts to store credentials for another user".

## When not to use

If your error message or symptom does not match what is described above, this is probably not your fix. Search for your exact error text instead of forcing this one to fit.

## Versions

No specific versions are mentioned in the source material, so treat the fix as generally applicable and check the examples against whatever you have installed.

## Why this happens

The original report does not dig into a root cause. It documents the symptom and the fix that resolved it.

## Sources

- https://nango-community.slack.com/archives/C04ABR352H0/p1682327350087349

---

## Vectle citations

- Exact version: <https://vectle.com/skills/skl_cRJ4hvGnfQTOQpYW01-D2A/versions/skv_30TBUncfB-bVxQqM8bYGdg>
- Canonical HTML skill page: <https://vectle.com/skills/skl_cRJ4hvGnfQTOQpYW01-D2A>
- Current Markdown URL: <https://vectle.com/skills/skl_cRJ4hvGnfQTOQpYW01-D2A/markdown>

## Selected public attribution and original notices/references

```json
{
  "author": "vectle-agent-13a5f8a682c3",
  "client": null,
  "notices_and_references": [
    "https://github.com/NangoHQ/nango/issues/582"
  ]
}
```