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

> A network client can exhaust memory in rclone's S3 server by sending oversized multipart headers, causing denial of service.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 10 Sep 2026
- **Updated:** 10 Sep 2026
- **Also known as:** BIT-rclone-2026-88045, DEBIAN-CVE-2026-88045, GHSA-2p48-j3qc-rx9f, GO-2026-6456, MINI-587c-qp29-rmj4, MINI-c5fv-5hr7-87fm, MINI-pmx8-9q4r-qrf9, MINI-ww7r-p9j8-4w38, UBUNTU-CVE-2026-88045

## What is CVE-2026-88045?

CVE-2026-88045 is a high-severity denial of service vulnerability in rclone, published on 10 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### 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.

Weakness: CWE-789 (Memory Allocation with Excessive Size Value)

## Which versions are affected by CVE-2026-88045?

4 open source packages ship an affected version, including github.com/rclone/rclone and rclone.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/rclone/rclone` | Go | From 1.75.0 | 1.75.1 |
| `github.com/rclone/rclone` | Go | From 1.75.0 | 1.75.1 |
| `github.com/rclone/rclone` | Go | From 1.75.0 | 1.75.1 |
| `rclone` | Bitnami | From 1.75.0 | 1.75.1 |

## How do I fix CVE-2026-88045?

Upgrade github.com/rclone/rclone to 1.75.1 or later.

## Is CVE-2026-88045 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-88045 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-88045 and fix it if it is affected.

What it is: CVE-2026-88045 is a high-severity denial of service vulnerability in rclone, published on 10 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-88045 exists.

Affected packages and fixed versions:
- github.com/rclone/rclone (Go): affected from 1.75.0; fixed in 1.75.1
- github.com/rclone/rclone (Go): affected from 1.75.0; fixed in 1.75.1
- github.com/rclone/rclone (Go): affected from 1.75.0; fixed in 1.75.1
- rclone (Bitnami): affected from 1.75.0; fixed in 1.75.1

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-88045/ (Markdown: https://insights.sbomify.com/CVE-2026-88045/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-88045
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-88045
- OSV: https://osv.dev/vulnerability/CVE-2026-88045

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-88045/
Summaries are generated and may contain mistakes; the official description above is the record.