EUVD-2026-75588
GHSA-2p48-j3qc-rx9f
Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Anonymous serve-s3 requires no credentials (PR:N, AV:N); impact is availability-only from memory exhaustion with no confidentiality or integrity effect.
Primary rating from Vendor (GitHub_M).
CVSS VectorVendor: GitHub_M
Lifecycle Timeline
7DescriptionCVE.org
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.
AnalysisAI
Memory exhaustion in rclone 1.75.0's serve S3 multipart upload handler allows remote attackers to exhaust process or host memory and permanently block request handlers by sending UploadPart requests that declare a large Content-Length but deliver no body bytes. The handler in cmd/serve/s3/multipart.go pre-allocates lib/pool pages sized to the attacker-controlled Content-Length header before any body bytes arrive, and the waitForTurn scheduling mechanism admits one additional oversized part even when --multipart-streaming-buffer-limit is active, partially bypassing the intended cap. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires the target to be running 'rclone serve s3' using rclone v1.75.0 specifically - the multipart streaming feature was introduced in this version and the vulnerability was introduced with it. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The provided CVSS 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) is accurate for the most exposed deployment case - anonymous rclone serve s3 instances with no --auth-key configured, which require zero credentials. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | Full exploit scenario with step-by-step reproduction available after sign-in. |
| Remediation | Upgrade to rclone v1.75.1, which removes the pre-emptive buffer reservation tied to client-declared Content-Length so that memory is allocated only as body bytes arrive - confirmed by commits 7c1dfd99f3e6a22fcefd8686cc478226a15e63a1 and ab1f458013aaf6356e4bdeca61f7cb9139f8eb86 and the vendor advisory at https://github.com/rclone/rclone/security/advisories/GHSA-2p48-j3qc-rx9f. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, identify all systems running rclone 1.75.0 with serve S3 functionality enabled and apply network access restrictions to limit exposure. …
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External POC / Exploit Code
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