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Vulnerability · Published Sep 10, 2026 · Assigned by GitHub_M

CVE-2026-88045rclone: S3 multipart declared-length memory exhaustion

High 7.5

In plain English

A high-severity security flaw in rclone from rclone. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 50% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.5High
Exploit odds (30 days)0.6%top 49.6% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack toolingNoneno public tooling known

Official description

rclone is a command-line program to sync files and directories to and from different cloud storage providers. From 1.75.0 until 1.75.1, the serve S3 streamed multipart path in cmd/serve/s3/multipart.go passes attacker-controlled contentLength to multipart.NewRW().Reserve before reading request-body bytes. waitForTurn admits the current part and one oversized part when the buffer is empty despite --multipart-streaming-buffer-limit, and lib/pool allocates 1 MiB pages according to Content-Length or X-Amz-Decoded-Content-Length. A network client can retain or multiply these reservations without sending the declared body, exhausting process or host memory or permanently blocking request handlers. Anonymous S3 deployments require no credentials, while deployments using auth_key require an accepted S3 key. This issue is fixed in version 1.75.1.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12rcloneno fix listedDEBIAN-CVE-2026-88045
Debian:13rcloneno fix listedDEBIAN-CVE-2026-88045
Gogithub.com/rclone/rclone1.75.1GHSA-2p48-j3qc-rx9f
Gogithub.com/rclone/rclone1.75.1GO-2026-6456
Ubuntu:26.10rcloneno fix listedUBUNTU-CVE-2026-88045

Affected products (as reported)

VendorProductVersions
rclone rclone >= 1.75.0, < 1.75.1

Weakness: CWE-789 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References