CVE-2026-79781 rclone CVE debrief

Who should care

Defenders responsible for rclone serve s3 installations, particularly those with sensitive files and directories, should assess exposure and prioritize verification and remediation.

Why it matters

CVE-2026-79781 is a path traversal vulnerability in rclone serve s3 before version 1.74.4 that allows attackers to read and overwrite root-level files. Defenders should prioritize verifying and updating installations, restricting access to sensitive files and directories, and monitoring for suspicious activity.

• Read and overwrite root-level files
• Escape bucket namespace and access files in serve root directory
• Potential data breaches and unauthorized modifications

Technical summary

The vulnerability allows attackers to read and overwrite root-level files by using dot-dot segments in S3 object keys. This is possible because the rclone serve s3 application does not properly sanitize object keys, allowing an attacker to escape the bucket namespace and access files in the serve root directory. Affected product context indicates that rclone serve s3 installations before version 1.74.4 are vulnerable. Defenders should prioritize verifying and updating installations, restricting access to sensitive files and directories, and monitoring for suspicious activity.

Defensive priority

Defenders should prioritize verifying and updating rclone serve s3 installations to version 1.74.4 or later, and restrict access to sensitive files and directories.

Recommended defensive actions

• Verify and update rclone serve s3 installations to version 1.74.4 or later
• Restrict access to sensitive files and directories
• Monitor for suspicious activity and implement compensating controls
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The vulnerability is described in the CVE record and NVD vulnerability detail page. The source references provide additional information about the vulnerability and its impact. Evidence limits suggest that defenders verify installations, review official advisories, and monitor for suspicious activity. Known affected scope includes rclone serve s3 before version 1.74.4, but specific deployments require verification.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.