Bug 2537399 - CVE-2026-88018 rclone: rclone serve s3: --auth-proxy without --auth-key authenticates nobody - full SigV4 signature bypass [fedora-all]
Summary: CVE-2026-88018 rclone: rclone serve s3: --auth-proxy without --auth-key authe...
Keywords:
Status: NEW
Alias: None
Product: Fedora
Classification: Fedora
Component: rclone
Version: rawhide
Hardware: Unspecified
OS: Unspecified
urgent
urgent
Target Milestone: ---
Assignee: Mikel Olasagasti Uranga
QA Contact: Fedora Extras Quality Assurance
URL:
Whiteboard: {"flaws": ["9811b395-133d-4f8f-b886-8...
Depends On:
Blocks: CVE-2026-88018
TreeView+ depends on / blocked
 
Reported: 2026-09-21 13:55 UTC by Marian Rehak
Modified: 2026-09-21 13:55 UTC (History)
2 users (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed:
Type: ---
Embargoed:


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Description Marian Rehak 2026-09-21 13:55:32 UTC
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.

rclone is a command-line program to sync files and directories to and from different cloud storage providers. Prior to 1.75.1, rclone serve s3 configured with --auth-proxy but without --auth-key allows authPairMiddleware to register any client-chosen accessKeyID with an empty ws.s3Secret. gofakes3 then verifies the request’s SigV4 signature against that same empty secret, while Server.auth passes the access key identifier as both the user and authentication value to the proxy without an independent per-identity secret. An unauthenticated network attacker can therefore choose an arbitrary access key, sign with an empty secret, and reach whatever backend the auth-proxy script resolves for that identity. This issue is fixed in version 1.75.1.


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