Cross-tenant file disclosure via unbound S3 keys
Published Jul 7, 2026 · Updated Jul 7, 2026
Authorization bypass in Labring FastGPT before 4.15.0-beta5 allows remote attackers to read cross-tenant files through S3 keys. Two file handlers authorize an app or dataset unrelated to the requested object, then sign or read the request-supplied S3 key without binding it to the caller's team. A public share link to any app reaches the chat-file path without authentication, while the dataset path requires write access to any dataset; both disclose files only when a victim object key is known.
Summary
What happened
Authorization bypass in Labring FastGPT before 4.15.0-beta5 allows remote attackers to read cross-tenant files through S3 keys. Two file handlers authorize an app or dataset unrelated to the requested object, then sign or read the request-supplied S3 key without binding it to the caller's team. A public share link to any app reaches the chat-file path without authentication, while the dataset path requires write access to any dataset; both disclose files only when a victim object key is known.
The record
- CVE
- CVE-2026-55418
- Published
- Jul 7, 2026
- Updated
- Jul 7, 2026
- Vendor
- Labring
- Product
- FastGPT
- Classifications
- CWE-639, T1530
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jul 7, 2026CVE publishedPublication date reported by the CVE source.
- Jul 7, 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=< 4.15.0-beta5
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
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- Cross-tenant S3 key endpoint proof of conceptproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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