vulnerability / NVI-00014021 / Revision 1
rclone serve s3: --auth-proxy without --auth-key authenticates nobody - full SigV4 signature bypass
GitHub lists this reviewed advisory for github.com/rclone/rclone. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.
This report has not inspected your inventory, configuration, deployed build, reachability or evidence. A catalog listing and a severity score do not establish exposure or compromise.
01 / Meaning
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9.8 critical
GitHub source severity; exploitability and local consequence require separate evidence.
As of · GitHub Advisory Database
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
github.com/rclone/rclone
source listed< 1.75.1
### Summary `rclone serve s3`'s handler chain, when `--auth-proxy` is configured, is (outermost first): `authPairMiddleware` -> `proxyAuthMiddleware` -> gofakes3's own SigV4-verifying handler. `authPairMiddleware` parses the accessKeyID straight out of the incoming request's own `Authorization` header (entirely client-controlled) and registers `{accessKey: ws.s3Secret}` into gofakes3's shared credential store via `AddAuthKeys`, for EVERY access key any client presents - not just ones previously known to the server. `ws.s3Secret` defaults to `""` whenever `--auth-key` is not set, which the `--auth-proxy` documentation (and the reference `bin/test_proxy.py`) presents as a complete, standalone authentication mechanism requiring no other flag - matching how it's used for `serve webdav`/`ftp`/`sftp`. gofakes3's SigV4 verification then checks the request's signature against exactly the secret `authPairMiddleware` just registered for that same client-chosen key. An empty string is a valid HMAC key, so a caller can trivially compute a correct SigV4 signature for ANY access key ID of their choosing using an empty secret, and verification passes. Crucially, the auth-proxy script never rec
03 / Response
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- investigate
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04 / Limits
What this report cannot establish
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05 / Provenance
Sources you can inspect
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- GHSA-xwwr-4h3p-r22c ↗
GitHub Advisory Database · vendor advisory
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- Revision 1 ·
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