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GeezerVison is showing github.com — security: add ACL check for WebSocket subscriptions by melvincarvalho · Pull Request #1840 · nodeSolidServer/node-solid-server

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@melvincarvalho

@melvincarvalho melvincarvalho commented Jan 7, 2026

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Summary

Check WAC read permission before allowing WebSocket subscriptions. This prevents information leakage via notifications to unauthorized users.

Changes

  • Add authorizeSubscription callback for solid-ws
  • Check ACL read access before allowing subscription
  • Denied subscriptions receive err <url> forbidden
  • Currently treats all WS connections as anonymous (see note below)

Dependencies

⚠️ This PR requires nodeSolidServer/node-solid-ws#29 to be merged and released first.

The solid-ws package needs the new authorize callback option before this can work.

Future enhancement

Currently all WebSocket connections are treated as anonymous for ACL purposes. This still prevents the main vulnerability (anonymous users subscribing to private resources).

Full authenticated WebSocket subscriptions would require either:

  • Parsing session cookies and looking up the session
  • Validating Authorization header bearer tokens

This can be added in a follow-up PR.

Fixes #1334

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@melvincarvalho
security: add ACL check for WebSocket subscriptions
03b5ff4 
Check WAC read permission before allowing WebSocket subscriptions.
This prevents information leakage via notifications to unauthorized users.

- Add authorizeSubscription callback for solid-ws
- Check ACL read access before allowing subscription
- Deny subscription returns 'err <url> forbidden'
- Currently treats all WS connections as anonymous (TODO: auth integration)

Depends on: nodeSolidServer/node-solid-ws#29
Fixes nodeSolidServer#1334
@melvincarvalho

melvincarvalho commented Jan 7, 2026

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For historical context, this issue was first raised in 2015 (#143) and Tim Berners-Lee described it as a "serious bug":

the lack of authentication is a serious bug with the current protocol

— @timbl in solid/notifications#3
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@bourgeoa

bourgeoa commented Jan 7, 2026

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@melvincarvalho can you recreate your PR to https://github.com/nodeSolidServer/node-solid-server/tree/websocket-acl-check
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Websockets does not check .acl

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2 participants

@melvincarvalho @bourgeoa
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