# GHSA-mjcr-rqjg-rhg3: Implementation trusts the "me" field returned by the authorization server without verifying it

> Attackers can impersonate any user by exploiting unverified IndieAuth identifiers, allowing unauthorized account access.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 24 Nov 2020

## What is GHSA-mjcr-rqjg-rhg3?

GHSA-mjcr-rqjg-rhg3 is an authentication bypass vulnerability in datasette-indieauth, published on 24 Nov 2020. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

### Impact

A malicious user can sign in as a user with any IndieAuth identifier. This is because the implementation does not verify that the final `"me"` URL value returned by the authorization server belongs to the same domain as the initial value entered by the user.

### Patches

Version 1.1 fixes this issue.

### Workarounds

There is no workaround. Upgrade to 1.1 immediately.

### References

- [Security Considerations: Differing User Profile URLs](https://indieauth.spec.indieweb.org/#differing-user-profile-urls-li-1) in the IndieAuth specification.

### For more information

If you have any questions or comments about this advisory:

* Open an issue in [simonw/datasette-indieauth](https://github.com/simonw/datasette-indieauth/issues)

## Which versions are affected by GHSA-mjcr-rqjg-rhg3?

2 open source packages ship an affected version, including datasette-indieauth.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `datasette-indieauth` | PyPI | From 1.0 | 1.1 |
| `datasette-indieauth` | PyPI | From 1.0 | 1.1 |

## How do I fix GHSA-mjcr-rqjg-rhg3?

Upgrade datasette-indieauth to 1.1 or later.

## Is GHSA-mjcr-rqjg-rhg3 being exploited?

There is no known exploitation of GHSA-mjcr-rqjg-rhg3 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for GHSA-mjcr-rqjg-rhg3 and fix it if it is affected.

What it is: GHSA-mjcr-rqjg-rhg3 is an authentication bypass vulnerability in datasette-indieauth, published on 24 Nov 2020. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of GHSA-mjcr-rqjg-rhg3 in the wild and no public exploit code.

Affected packages and fixed versions:
- datasette-indieauth (PyPI): affected from 1.0; fixed in 1.1
- datasette-indieauth (PyPI): affected from 1.0; fixed in 1.1

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/GHSA-mjcr-rqjg-rhg3/ (Markdown: https://insights.sbomify.com/GHSA-mjcr-rqjg-rhg3/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/GHSA-mjcr-rqjg-rhg3

---
From sbomify Insights: https://insights.sbomify.com/GHSA-mjcr-rqjg-rhg3/
Summaries are generated and may contain mistakes; the official description above is the record.