CVE-2026-79781
Received Received - Intake

Path Traversal in Rclone S3 Server

Publication date: 2026-08-25

Last updated on: 2026-08-25

Assigner: VulnCheck

Description
rclone serve s3 before 1.74.4 contains a path traversal vulnerability that allows attackers to read and overwrite root-level files by using dot-dot segments in S3 object keys. Attackers can send requests with object keys like ../root-secret.txt to escape the bucket namespace and access files in the serve root directory.

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Meta Information

Published
2026-08-25
Last Modified
2026-08-25
Generated
2026-08-25
AI Q&A
2026-08-25
EPSS Evaluated
N/A
NVD
CVE-2026-79781
EUVD
EUVD-2026-65539

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
rclone rclone to 1.74.4 (exc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-22 The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.

Attack-Flow Graph

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Executive Summary

This is a path traversal vulnerability in rclone's serve s3 feature before version 1.74.4. Attackers can use dot-dot segments in S3 object keys like ../root-secret.txt to escape the bucket directory and access or overwrite files in the server's root directory.

Detection Guidance

To detect this vulnerability, monitor rclone serve s3 instances for requests containing dot-dot segments like ../ in S3 object keys. Check logs for patterns such as GET /bucket/../ or similar traversal attempts. Use tools like grep to search logs for '../' in object key fields.

Impact Analysis

This vulnerability allows attackers to read sensitive files or overwrite critical system files on the server. If the server allows anonymous access, exploitation can occur without authentication, leading to unauthorized file disclosure or modification.

Compliance Impact

This vulnerability could lead to unauthorized access or modification of sensitive files, which may violate data protection requirements under GDPR (e.g., unauthorized access to personal data) and HIPAA (e.g., exposure of protected health information). Organizations using vulnerable rclone versions risk non-compliance if such incidents occur.

Mitigation Strategies

Upgrade rclone to version 1.74.4 or later immediately. If upgrading is not possible, disable the serve s3 functionality or restrict access to authenticated users only. Review and filter incoming S3 object keys to reject those containing path traversal sequences like ../.

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