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High, CVSS 7.3amended

rclone: FTP cross-session auth-proxy backend confusion

CVE-2026-88017GHSA-c476-6w5q-jw77

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (github.com/rclone/rclone 1.75.1), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
7.3 · CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N
EPSS
  • CVE-2026-88017: 0.23% estimated exploitation activity in the next 30 days; percentile 14.40 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Summary The FTP auth-proxy driver stores one obscured password per username in a server-wide map. It does not bind the credential or returned VFS to the authenticated FTP session. If two accepted credentials use the same username but resolve to different proxy backends, the later login overwrites the map entry. Subsequent operations on the first, still-authenticated session are re-authorized with the later session's password and execute against the later session's backend. This is not exploitable in every auth-proxy deployment. It requires a proxy that accepts distinct credentials for the same username and returns different roots or backend configurations, plus a later login while the attacker's session remains open. The behavior is nevertheless within the supported model: cmd/serve/proxy keys VFS entries by username, authentication material, and client IP specifically so a new credential can produce a fresh backend. Confirmed affected versions are v1.75.0 and development commit…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 3 · amended ·

    Amended from ghsa record GHSA-c476-6w5q-jw77

  2. Revision 2 · amended ·

    Amended from osv record GO-2026-6458

  3. Revision 1 · created ·

    Published from osv record GHSA-c476-6w5q-jw77

Agent brief

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# Patch Next advisory brief: CVE-2026-88017

Advisory: rclone: FTP cross-session auth-proxy backend confusion
IDs: CVE-2026-88017, GHSA-c476-6w5q-jw77
Record: https://patchnext.com/advisories/cve-2026-88017 (revision 3, source checked 26 Oct 2026, 15:29 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/rclone/rclone 1.75.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/rclone/rclone: affected >= 1.64.0, <= 1.75.0; fixed in 1.75.1

## Suggested inspection (read-only)
- Go github.com/rclone/rclone: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/rclone/rclone.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-c476-6w5q-jw77 (OSV record GHSA-c476-6w5q-jw77 lists affected ranges: Go github.com/rclone/rclone >=1.64.0 <1.75.1 (fixed))
- Verified: https://osv.dev/vulnerability/GO-2026-6458 (OSV record GO-2026-6458 lists affected ranges: Go github.com/rclone/rclone >=1.64.0 <1.75.1 (fixed))
- Verified: https://github.com/advisories/GHSA-c476-6w5q-jw77 (GitHub-reviewed advisory GHSA-c476-6w5q-jw77 lists affected ranges: Go github.com/rclone/rclone >=1.64.0 <=1.75.0)

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