rclone local --metadata applies attacker-controlled mode/uid - setuid binary planted from an untrusted remote

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

2.0 · CVSS:4.0/AV:L/AC:H/AT:P/PR:N/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X · score source

EPSS

• CVE-2026-79783: 0.23% estimated exploitation activity in the next 30 days; percentile 13.58 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary When writing an object with metadata, the local backend applies the source-supplied mode, uid, and gid verbatim: it parses mode as an octal integer and passes it straight into os.Chmod(o.path, os.FileMode(umode)), and passes uid/gid straight into os.Chown. The value is never masked to permission bits, so any value with Go's ModeSetuid (1<<23) or ModeSetgid (1<<22) bit set causes the setuid/setgid bit to be applied. Because both the file content and its metadata come from the (attacker-controlled) source remote, an attacker stores a binary of their choosing with mode = 40000755 (and uid = 0); when the victim runs rclone copy -M <remote: /dest, rclone writes the attacker's binary and makes it setuid. If the victim runs rclone as root (typical for system backup/restore), the uid=0 chown plus setuid produces a root-owned setuid binary with attacker content — any local user then escalates to root. When rclone runs as a non-root service user, the planted setuid binary is owned by…

Published by the source

5 Aug 2026, 20:03 UTC

Last modified by the source

25 Sep 2026, 14:25 UTC

Source last checked

26 Oct 2026, 15:28 UTC

1. Revision 4 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-945v-v9p3-v5xw

2. Revision 3 · amended · 25 Oct 2026

   Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

3. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GO-2026-6190

4. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-945v-v9p3-v5xw

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# Patch Next advisory brief: CVE-2026-79783

Advisory: rclone local `--metadata` applies attacker-controlled mode/uid - setuid binary planted from an untrusted remote
IDs: CVE-2026-79783, GHSA-945v-v9p3-v5xw
Record: https://patchnext.com/advisories/cve-2026-79783 (revision 4, source checked 26 Oct 2026, 15:28 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Low (CVSS 2.0)
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 1.74.4. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/rclone/rclone: affected <= 1.74.3; fixed in 1.74.4

## 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-945v-v9p3-v5xw (OSV record GHSA-945v-v9p3-v5xw lists affected ranges: Go github.com/rclone/rclone >=0 <1.74.4 (fixed))
- Verified: https://osv.dev/vulnerability/GO-2026-6190 (OSV record GO-2026-6190 lists affected ranges: Go github.com/rclone/rclone >=0 <1.74.4 (fixed))
- Verified: https://github.com/advisories/GHSA-945v-v9p3-v5xw (GitHub-reviewed advisory GHSA-945v-v9p3-v5xw lists affected ranges: Go github.com/rclone/rclone >=0 <=1.74.3)

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