Proof-of-concept code is out for ten flaws rclone fixed in 1.75.2

Proof-of-concept code is out for ten flaws rclone fixed in 1.75.2

26 October 2026: Italy's national cybersecurity agency says working proof-of-concept code is now public for ten vulnerabilities in rclone, the open-source tool many companies use to copy, sync and serve files across S3, Backblaze B2, WebDAV and dozens of other storage services. All ten affect rclone 1.75.1 and earlier and are fixed in 1.75.2, which the project released on 9 October. The most serious, CVE-2026-116191, lets an unauthenticated client create, overwrite, move or delete files outside the folder that rclone serve webdav is meant to expose.

Not yet independently verified. The CVE numbers and CVSS 4.0 scores come from CSIRT Italia, which maps them to rclone's own GitHub advisories; rclone's advisories still list no CVE and score the same flaws lower under CVSS 3.1. We have not seen the proof-of-concept code ourselves. We will update this when it can be confirmed, and remove this note.

CSIRT Italia published its alert, AL02/261026/CSIRT-ITA, on the morning of 26 October and rated its systemic impact critical (77.82). It reports no exploitation so far.

The flaws that matter most on a server

The risk is highest where rclone runs as a service rather than as a command an administrator types. CSIRT Italia scores the batch under CVSS 4.0:

• CVE-2026-116191 (8.7): path traversal through .. in WebDAV requests, unauthenticated, outside the served root
• CVE-2026-116192 (8.2): server-side request forgery through named remotes in --rc-serve, which can send HTTP or NetStorage requests, configured headers and valid signatures to a host the attacker controls
• CVE-2026-116189 (7.7): the self-update check trusted unsigned data in the signed SHA256SUMS file, so someone able to tamper with the download channel could install a modified rclone
• CVE-2026-116194 (7.6): the pCloud OAuth callback did not check its state parameter, so a web page visited during authorisation could repoint the remote at the attacker's storage
• CVE-2026-116195 (7.0): .rclonelink names escaping the destination with --links and --metadata, an incomplete fix of an earlier CVE; run as root, it can change the parent of a backup destination
• CVE-2026-116193 (6.9): serve webdav skipped authentication for every OPTIONS request
• CVE-2026-116188 (6.9): an integer overflow in serve s3 multipart accounting bypassed the memory limit
• CVE-2026-116190 (6.3): the WebDAV backend forwarded custom credential headers to a different host on redirect
• CVE-2026-116187 (6.1): with serve s3 --auth-proxy, one tenant could interfere with another tenant's multipart uploads
• CVE-2026-116196 (6.0): the B2 backend could leak its account token and SSE-C encryption keys to a --b2-download-url host on redirect

Two more fixes the alert leaves out

Rclone itself published twelve advisories on 9 October, all fixed in 1.75.2. The two not in the Italian list are a presigned upload URL in serve s3 that could read any bucket, and global --header values that survived an HTTPS to HTTP redirect on the same port. The same release also moved the build to Go 1.26.9, which closes about fifteen Go standard library CVEs in HTTP/2, TLS and template handling, and updated golang.org/x/net and gRPC.

Rclone's own scores are lower, between 3.7 and 7.5 under CVSS 3.1, and only the WebDAV traversal and the self-update bypass are rated high there.

Where to look first

Check every machine and container image that runs rclone serve (webdav, s3, http or docker) or exposes the remote control API, then any scheduled backup job that uses --links, B2 with a custom download URL, or pCloud. A copy installed through a Linux distribution's package manager can lag behind the project's own builds, so running rclone version on each host is the reliable check. Our file sync category lists 10 products and our server backup category 20, several of which can stand in for a self-run rclone server where that is easier to keep patched.

Related on TrustList:

• Commvault patches critical command execution flaw in its CVFS storage
• Veeam fixes critical remote code flaw in Backup & Replication 12

Sources

• ACN CSIRT Italia: Rclone, disponibili PoC per numerose vulnerabilita (AL02/261026/CSIRT-ITA), 26 October 2026
• rclone: security advisories on GitHub (12 published 9 October 2026), 9 October 2026
• rclone changelog, v1.75.2, 9 October 2026