STS token disclosure via scheme-downgrade redirect
Published Aug 25, 2026 · Updated Aug 28, 2026
Cleartext credential transmission in rclone before 1.74.4 allows adjacent attackers to capture AWS STS session tokens through S3 redirects. The backend/s3 s3RedirectCrossesHost check compares only host values, so a same-host HTTPS-to-HTTP redirect leaves X-Amz-Security-Token attached to the plaintext request. Exposure requires an S3 remote using temporary credentials, a downgrade redirect, and an observer on the resulting HTTP path; the disclosed token remains usable only for its validity period.
Summary
What happened
Cleartext credential transmission in rclone before 1.74.4 allows adjacent attackers to capture AWS STS session tokens through S3 redirects. The backend/s3 s3RedirectCrossesHost check compares only host values, so a same-host HTTPS-to-HTTP redirect leaves X-Amz-Security-Token attached to the plaintext request. Exposure requires an S3 remote using temporary credentials, a downgrade redirect, and an observer on the resulting HTTP path; the disclosed token remains usable only for its validity period.
The record
- CVE
- CVE-2026-79782
- Published
- Aug 25, 2026
- Updated
- Aug 28, 2026
- Vendor
- Rclone
- Product
- rclone
- Classifications
- CWE-319, CWE-522, T1557
- Attack vector
- adjacent
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 25, 2026CVE publishedPublication date reported by the CVE source.
- Aug 28, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0 <1.74.4
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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