Integer overflow in rclone serve s3 lets attackers exhaust memory
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Attack requirements
- None
- Impact type
- —
- Confidentiality · integrity · availability
- None · None · Low
- Fix status
- Partial Red Hat: 2 without a fix
Attack profile from CVSS 4.0 · CNA. Fix status from CNA and Red Hat.
Summary
rclone serve s3 versions from 1.75.0 before 1.75.2 contain an integer overflow in multipart reorder-memory accounting (CWE-190) that bypasses the configured buffer limit. An unauthenticated remote attacker can make the counter wrap so that out-of-order parts stay in memory, exhausting the host.
Written with Claude Haiku 5.5 from the sources below · 2026-11-06
Description from the CNA
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.
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
Remediation
Upgrade rclone to version 1.75.2. Red Hat lists Cryostat 4 and Red Hat Advanced Cluster Management for Kubernetes 2 as affected without a fix and states that no plan is available.
Written with Claude Haiku 5.5 from the sources below · 2026-11-06
- Fix · CNA rclone (rclone) Fixed in 1.75.2
Fixed in the same release
Records fixed by the same vendor advisory or release, as the CNA lists them.
- Release ·
rclone 1.75.2
9 records Highest priority Priority HIGH 4 HIGH, 2 MEDIUM, 3 LOW
Other records, highest priority first
- TI-2026-80211 Authentication bypass in rclone serve webdav via OPTIONS requestsPriority HIGH 70
- TI-2026-80207 Signature verification bypass in rclone selfupdatePriority HIGH 69
- TI-2026-80212 Cross-site request forgery in Rclone pCloud OAuth callbackPriority HIGH 68
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Cryostat 4 | Affected | No fix yet: Fix deferred |
| Red Hat Advanced Cluster Management for Kubernetes 2 | Affected | No fix yet: Fix deferred |
Timeline
- 2026-10-25 Threatist record created from CVE-2026-116188
- 2026-10-26 Priority changed: MEDIUM → LOW
- 2026-10-27 Alias added: GHSA-6475-788v-w6c3
- 2026-11-04 CISA SSVC decision points changed
- 2026-11-04 Priority changed: LOW → HIGH
- 2026-11-06 Affected versions changed · Red Hat
- 2026-11-06 CVSS score added · Red Hat
References
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-2026-42602 Path traversal in rclone CVSS 3.1HIGH 8.8
- TI-2026-39407 rclone: Unvalidated symlink target in local `--links` — arbitrary file write from an untrusted remote CVSS 3.1HIGH 8.8
- TI-2026-80211 Authentication bypass in rclone serve webdav via OPTIONS requests CVSS 4.0MEDIUM 6.9
Sources
- CVE-2026-116188 · CVE Program
- CVE-2026-116188 · NVD
- FIRST EPSS
- GHSA-6475-788v-w6c3 · GitHub Advisory Database · CC BY 4.0
- CVE-2026-116188 · 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