CVE-2026-88018 rclone - Authentication Bypass

rclone < 1.75.1 contains an authentication bypass caused by authPairMiddleware registering any client-chosen accessKeyID with an empty secret in s3 serve mode with --auth-proxy but without --auth-key, letting unauthenticated network attackers access backend services, exploit requires no authentication.

CVSS base score 9.8 /10
Critical
CISA KEV
Not listed
Public exploit
None known
Authentication
Not required
EPSS
0.51% chance of exploitation in 30 days
View the NVD record ↗

Details

Type
Authentication Bypass
Impact
Broken Authentication
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Published
10 September 2026
Updated
15 October 2026
Weakness
CWE-287

Vendor fix

Update to version 1.75.1 or later.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

References

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