Headline
GHSA-3qjf-qh38-x73v: Unauthenticated Miniflux user can bypass allowed networks check to obtain Prometheus metrics
Impact
An unauthenticated user can retrieve Prometheus metrics from a publicly reachable Miniflux instance where the METRICS_COLLECTOR configuration option is enabled and METRICS_ALLOWED_NETWORKS is set to 127.0.0.1/8 (the default).
Patches
PR #1745 fixes the problem. Available in Miniflux >= 2.0.43.
Workarounds
Set METRICS_COLLECTOR to false (default) or run Miniflux behind a trusted reverse-proxy.
References
- https://miniflux.app/docs/configuration.html#metrics-collector
- https://miniflux.app/docs/configuration.html#metrics-allowed-networks
Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
Related news
Miniflux is a feed reader. Prior to version 2.0.43, an unauthenticated user can retrieve Prometheus metrics from a publicly reachable Miniflux instance where the `METRICS_COLLECTOR` configuration option is enabled and `METRICS_ALLOWED_NETWORKS` is set to `127.0.0.1/8` (the default). A patch is available in Miniflux 2.0.43. As a workaround, set `METRICS_COLLECTOR` to `false` (default) or run Miniflux behind a trusted reverse-proxy.
Miniflux is a feed reader. Since v2.0.25, Miniflux will automatically proxy images served over HTTP to prevent mixed content errors. When an outbound request made by the Go HTTP client fails, the `html.ServerError` is returned unescaped without the expected Content Security Policy header added to valid responses. By creating an RSS feed item with the inline description containing an `<img>` tag with a `srcset` attribute pointing to an invalid URL like `http:a<script>alert(1)</script>`, we can coerce the proxy handler into an error condition where the invalid URL is returned unescaped and in full. This results in JavaScript execution on the Miniflux instance as soon as the user is convinced (e.g. by a message in the alt text) to open the broken image. An attacker can execute arbitrary JavaScript in the context of a victim Miniflux user when they open a broken image in a crafted RSS feed. This can be used to perform actions on the Miniflux instance as that user and gain administrative ac...