CVE-2026-116193: Rclone serve webdav authentication bypass via OPTIONS requests

CVE-2026-116193 · Severity: medium · CVSS 5.3 · Published 2026-10-25

Rclone is a command-line file synchronization tool that can expose directories via WebDAV. The serve webdav component fails to enforce authentication for HTTP OPTIONS requests, allowing unauthenticated attackers to probe for the existence of files and directories on the server. An attacker can enumerate the file namespace and determine whether specific paths exist without providing valid credentials, exposing sensitive metadata even though file contents remain protected.

Technologies: Rclone. Vendors: Rclone.

Quick answers

Is CVE-2026-116193 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-116193 being exploited in the wild.
How severe is CVE-2026-116193?
Medium severity, with a CVSS score of 5.3, published 25 October 2026.
Which products and versions are affected?
Rclone 1.64.0 to 1.75.1.
Is there a fix for CVE-2026-116193?
Yes: fixed in 1.75.2. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-116193 attacked?
It is attacked over the network, in a software library.
Am I affected by CVE-2026-116193?
Check whether you run Rclone at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • Fixed in: 1.75.2

Technical details

The HTTP authentication middleware in lib/http/middleware.go unconditionally bypasses authentication for any OPTIONS request, not just legitimate CORS preflights, because it does not check for required preflight headers (Origin and Access-Control-Request-Method). In serve webdav, the WebDAV handler routes OPTIONS requests to the underlying golang.org/x/net/webdav library, which returns different Allow header values for existing files, existing directories, and non-existent paths, enabling an attacker to enumerate the namespace via response analysis. This affects all three authentication methods: --user/--pass, --htpasswd, and --auth-proxy.

Affected products

  • Rclone Rclone 1.64.0 to 1.75.1

Timeline

  • 2026-10-09: disclosed
  • 2026-10-25: advisory
  • 2026-10-09: patched: version 1.75.2 released

References

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