Dragonfly is an open source P2P-based file distribution and image acceleration system. Prior to 2.1.0, the first return value of a function is dereferenced even when the function returns an error. This can result in a nil dereference, and cause code to panic. This vulnerability is fixed in 2.1.0.

Affected: Go: github.com/dragonflyoss/dragonfly, Go: d7y.io/dragonfly/v2

### Impact We found two instances in the DragonFly codebase where the first return value of a function is dereferenced even when the function returns an error (figures 9.1 and 9.2). This can result in a nil dereference, and cause code to panic. The codebase may contain additional instances of the bug.

```golang request, err := source.NewRequestWithContext(ctx, parentReq.Url, parentReq.UrlMeta.Header) if err != nil { log.Errorf("generate url [%v] request error: %v", request.URL, err) span.RecordError(err) return err } ```

Eve is a malicious actor operating a peer machine. She sends a dfdaemonv1.DownRequest request to her peer Alice. Alice’s machine receives the request, resolves a nil variable in the server.Download method, and panics.

### Patches

- Dragonfy v2.1.0 and above.

### Workarounds

There are no effective workarounds, beyond upgrading.

### References

A third party security audit was performed by Trail of Bits, you can see the [full report](https://github.com/dragonflyoss/dragonfly/blob/main/docs/security/dragonfly-comprehensive-report-2023.pdf).

If you have any questions or comments about this advisory, please email us at [dragonfly-maintainers@googlegroups.com](mailto:dragonfly-maintainers@googlegroups.com).

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