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TI-2026-60044 Aliases CVE-2026-88018GHSA-xwwr-4h3p-r22c

rclone serve s3: --auth-proxy without --auth-key authenticates nobody - full SigV4 signature bypass

Priority HIGH 82CWE-287Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Security bypass
Confidentiality · integrity · availability
High · High · High
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-287.

Summary

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.0051 43rd percentileScored 2026-11-07
Fix Fixed rclone (rclone): 1.75.1github.com/rclone/rclone (Go): 1.75.1

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
Yes
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
rclonerclonebefore 1.75.11.75.1Patch availableCNA
—github.com/rclone/rclone (Go)before 1.75.11.75.1Patch availableGHSA-xwwr-4h3p-r22c
  • rclone Vendorrclone Affected before 1.75.1 Fixed in 1.75.1 Patch available CNA
  • github.com/rclone/rclone (Go) Vendor— Affected before 1.75.1 Fixed in 1.75.1 Patch available GHSA-xwwr-4h3p-r22c

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:rclone:rclone:*:*:*:*:*:*:*:*before 1.75.1Vulnerablerclone
  • cpe:2.3:a:rclone:rclone:*:*:*:*:*:*:*:* Versions before 1.75.1 Vulnerable ·rclone

Remediation

  • Fix · CNA rclone (rclone) Fixed in 1.75.1
  • Fix · GHSA-xwwr-4h3p-r22c github.com/rclone/rclone (Go) Fixed in 1.75.1 Advisory →

Vendor assessments

Red Hat

Red Hat's page for this CVE →

Not affected: 1 product
  • Red Hat

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-88018
  2. 2026-10-03 Alias added: GHSA-xwwr-4h3p-r22c

References

Patch 1

Advisory 2

Other 2

  • TI-2026-29802 RClone: Unauthenticated operations/fsinfo allows attacker-controlled backend instantiation and local command execution CVSS 4.0CRITICAL 9.2
  • TI-2026-29799 Rclone: Unauthenticated options/set allows runtime auth bypass, leading to sensitive operations and command execution CVSS 4.0CRITICAL 9.2
  • TI-2026-42602 Path traversal in rclone CVSS 3.1HIGH 8.8
  • TI-2026-39407 rclone: Unvalidated symlink target in local `--links` — arbitrary file write from an untrusted remote CVSS 3.1HIGH 8.8
  • TI-2026-80211 Authentication bypass in rclone serve webdav via OPTIONS requests CVSS 4.0MEDIUM 6.9
  • TI-2026-80206 Integer overflow in rclone serve s3 lets attackers exhaust memory CVSS 4.0MEDIUM 6.9
See all 23 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences