---
id: "CVE-2026-116188"
kind: "vulnerability"
aliases: ["CVE-2026-116188"]
title: "rclone: integer overflow in S3 multipart upload lets attackers exhaust memory"
severity: "medium"
cvss: 6.9
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["package", "rclone", "s3", "self-hosted"]
not_affected_if: ["client-only-use", "version-outside-range"]
published_at: "2026-10-25T14:16:58+00:00"
first_seen_at: "2026-10-25T14:41:23+00:00"
updated_at: "2026-10-25T14:42:40+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-116188", "first_seen_at": "2026-10-25T14:41:23+00:00"}]
---

# rclone: integer overflow in S3 multipart upload lets attackers exhaust memory

rclone serve s3 versions 1.75.0 before 1.75.2 miscount memory used for out-of-order multipart parts because a signed int64 counter wraps. An attacker sending two concurrent part uploads with huge declared lengths can bypass the configured buffer limit and exhaust host memory.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Run `rclone version` and check whether it reports a version from `1.75.0` up to, but not including, `1.75.2`
- Check whether `rclone serve s3` is running on the host, for example with `ps aux | grep "rclone serve s3"`

## Fix

- Upgrade rclone to `1.75.2` or later
- Until upgraded, stop exposing `rclone serve s3` to untrusted networks

## Timeline

- 2026-10-25T14:41:23+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-116188

## From the sources

rclone serve s3 versions 1.75.0 before 1.75.2 contain an integer overflow vulnerability in multipart reorder-memory accounting that bypasses the configured buffer limit. Attackers can open two concurrent current-part PUT requests declaring huge lengths to wrap the signed int64 counter and retain out-of-order parts in memory, exhausting the host.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_