EUVD-2026-65538
GHSA-fj78-v5f5-cphq
Severity by source
CVSS:4.0/AV:A/AC:H/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Adjacent network vector and high complexity reflect the required on-path position plus redirect precondition; no integrity or availability impact applies.
Primary rating from Vendor (VulnCheck).
CVSS VectorVendor: VulnCheck
CVSS:4.0/AV:A/AC:H/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Lifecycle Timeline
3DescriptionCVE.org
rclone before v1.75.0 fails to sanitize IBM IAM bearer tokens and SSE-C encryption keys during S3 redirect callbacks, allowing credentials to be preserved across scheme or host changes. Attackers observing network traffic from a trusted endpoint can capture reusable IBM IAM tokens on same-host HTTPS-to-HTTP downgrades or SSE-C keys on cross-origin redirects to access protected S3 objects.
AnalysisAI
Credential exposure in rclone before v1.75.0 allows network-adjacent attackers to capture IBM IAM bearer tokens during same-host HTTPS-to-HTTP redirect downgrades, or SSE-C customer-provided encryption keys during cross-origin S3 redirects. The S3 redirect callback in s3.go correctly strips X-Amz-Security-Token on host changes but omits IBM IAM Authorization headers and SSE-C key headers from its denylist, exploiting a gap in Go's built-in redirect sanitization that does not treat scheme downgrades as a credential boundary. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires three concurrent conditions: (1) the rclone client must be performing S3 operations using IBM IAM bearer token authentication or SSE-C customer-provided encryption keys - rclone deployments using only standard AWS SigV4 with STS tokens are not affected by the IBM IAM or SSE-C paths; (2) a trusted S3-compatible endpoint, gateway, or accelerator in the request path must issue an unsafe HTTP redirect - specifically, either a same-hostname HTTPS-to-HTTP scheme downgrade (for the IBM IAM token path) or a cross-origin redirect to a different hostname (for the SSE-C key path) - this is outside the attacker's direct control unless the gateway itself is compromised or misconfigured; (3) the attacker must hold a network-adjacent position capable of observing the plaintext HTTP traffic on the downgraded leg or the redirected request to the cross-origin host. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 4.0 score of 6.0 reflects meaningful but constrained real-world risk. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | A network-adjacent attacker positioned on the same subnet or acting as an on-path gateway between a rclone client and an S3-compatible endpoint configures or exploits a trusted gateway to issue an HTTPS-to-HTTP redirect on the same hostname for S3 GET requests. When rclone follows the redirect, Go's HTTP client retains the Authorization: Bearer header (IBM IAM token) because the hostname did not change, and rclone's callback does not strip it; the attacker captures the plaintext IBM IAM token from the downgraded HTTP leg and subsequently uses it to make authenticated requests directly to IBM Cloud Object Storage. … |
| Remediation | The vendor-released patch is rclone v1.75.0, which corrects the s3CheckRedirect callback to include IBM IAM authorization headers and SSE-C key headers in its redirect sanitization denylist. … Detailed patch versions, workarounds, and compensating controls in full report. |
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Same weakness CWE-200 – Information Exposure
View allSame technique Information Disclosure
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External POC / Exploit Code
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