Privilege escalation via unmasked special mode bits
Published Aug 25, 2026 · Updated Aug 25, 2026
Privilege escalation in rclone 1.74.3 and earlier allows attackers to gain the process owner's privileges via malicious source metadata. The local backend's writeMetadataToFile function passes source-controlled mode values directly to os.Chmod without removing setuid or setgid bits. Exploitation requires a metadata-preserving copy from an untrusted remote; a planted executable runs as root when rclone runs as root, or as its service account otherwise.
Summary
What happened
Privilege escalation in rclone 1.74.3 and earlier allows attackers to gain the process owner's privileges via malicious source metadata. The local backend's writeMetadataToFile function passes source-controlled mode values directly to os.Chmod without removing setuid or setgid bits. Exploitation requires a metadata-preserving copy from an untrusted remote; a planted executable runs as root when rclone runs as root, or as its service account otherwise.
The record
- CVE
- CVE-2026-79783
- Published
- Aug 25, 2026
- Updated
- Aug 25, 2026
- Vendor
- Rclone
- Product
- rclone
- Classifications
- CWE-732, T1548.001
- Attack vector
- local
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 25, 2026CVE publishedPublication date reported by the CVE source.
- Aug 25, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0 <1.74.4
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- Upstream setuid metadata proof of conceptproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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