vulnerability / NVI-00015360 / Revision 1
rclone: S3 backend does not strip X-Amz-Security-Token on a same-host HTTPS->HTTP redirect
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
Why it matters
Published affected context helps an owner decide what evidence to gather. This report has not examined your application.
3.1 low
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<= 1.74.3
## Vulnerability Details **File**: `backend/s3/s3.go` **Lines**: 1359-1380 (functions `s3CheckRedirect` / `s3RedirectCrossesHost`) ### Root Cause Commit `e7b1eb774` (released in v1.74.3) added a `CheckRedirect` policy for the S3 HTTP client whose purpose is to strip the `X-Amz-Security-Token` header (the AWS STS session token) whenever a redirect chain "crosses a host", so the token isn't forwarded to an unintended origin. `s3RedirectCrossesHost` decides this purely by comparing `url.URL.Host` (hostname[:port]); it never looks at `url.URL.Scheme`. A redirect that keeps the exact same host:port but changes the scheme from `https://` to `http://` therefore compares as "same host" and `X-Amz-Security-Token` is *not* stripped — it is sent again, this time over plaintext HTTP. ```go func s3RedirectCrossesHost(req *http.Request, via []*http.Request) bool { if len(via) == 0 { return false } host := via[0].URL.Host for _, redirect := range via[1:] { if redirect.URL.Host != host { return true } } return host != req.URL.Host } ``` ### Attack Scenario 1. The user configures an `s3` remote (or `--s3-endpoint` pointing at a self-hosted/third-party S3-compatible service) u
03 / Response
What to do next
- investigate
Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.
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04 / Limits
What this report cannot establish
- Customer inventory, deployment, reachability and exploitation have not been inspected.
05 / Provenance
Sources you can inspect
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- GHSA-gx4c-2hqx-cw2r ↗
GitHub Advisory Database · vendor advisory
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- Revision 1 ·
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