rclone: S3 multipart declared-length memory exhaustion
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Denial of service
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-789.
Summary
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.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- Poc
- Automatable
- Yes
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| rclone | rclone | 1.75.0 to before 1.75.1 | 1.75.1 | Patch available | CNA |
| — | github.com/rclone/rclone (Go) | 1.75.0 to before 1.75.1 | 1.75.1 | Patch available | GHSA-2p48-j3qc-rx9f |
- rclone Vendorrclone Affected 1.75.0 to before 1.75.1 Fixed in 1.75.1 Patch available CNA
- github.com/rclone/rclone (Go) Vendor— Affected 1.75.0 to before 1.75.1 Fixed in 1.75.1 Patch available GHSA-2p48-j3qc-rx9f
Remediation
- Fix · CNA rclone (rclone) Fixed in 1.75.1
- Fix · GHSA-2p48-j3qc-rx9f github.com/rclone/rclone (Go) Fixed in 1.75.1 Advisory →
Vendor assessments
Red Hat
Red Hat rating: Important. Red Hat's page for this CVE →
Not affected: 2 products
- Cryostat 4
- Red Hat Advanced Cluster Management for Kubernetes 2
Timeline
- 2026-10-02 Threatist record created from CVE-2026-88045
- 2026-10-03 Alias added: GHSA-2p48-j3qc-rx9f
- 2026-10-28 EPSS moved to the 50th–90th percentile
References
Other 6
- https://github.com/rclone/rclone/security/advisories/GHSA-2p48-j3qc-rx9f
- https://github.com/rclone/rclone/issues/9616
- https://github.com/rclone/rclone/commit/7c1dfd99f3e6a22fcefd8686cc478226a15e63a1
- https://github.com/rclone/rclone/commit/ab1f458013aaf6356e4bdeca61f7cb9139f8eb86
- https://github.com/rclone/rclone/releases/tag/v1.75.1
- https://github.com/rclone/rclone
More rclone vulnerabilities
- TI-2026-60044 rclone serve s3: --auth-proxy without --auth-key authenticates nobody - full SigV4 signature bypass CVSS 3.1CRITICAL 9.8
- TI-2026-29802 RClone: Unauthenticated operations/fsinfo allows attacker-controlled backend instantiation and local command execution CVSS 4.0CRITICAL 9.2
- TI-2026-29799 Rclone: Unauthenticated options/set allows runtime auth bypass, leading to sensitive operations and command execution CVSS 4.0CRITICAL 9.2
- TI-2026-60064 rclone: RC per-server auth-proxy bypass CVSS 3.1CRITICAL 9.1
- TI-2026-42602 Path traversal in rclone CVSS 3.1HIGH 8.8
- TI-2026-49967 rclone: Incomplete path validation allows backend root escape in serve restic CVSS 4.0HIGH 8.6
Sources
- CVE-2026-88045 · CVE Program
- CVE-2026-88045 · NVD
- FIRST EPSS
- GHSA-2p48-j3qc-rx9f · GitHub Advisory Database · CC BY 4.0
- CVE-2026-88045 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences