Unauthenticated S3 object access via path mismatch
Published May 11, 2026 · Updated May 11, 2026
Authentication bypass in Oxyno-zeta S3-Proxy before 5.0.0 allows remote attackers to access protected S3 objects via crafted paths. The authentication middleware matches encoded RequestURI paths while the bucket handler derives object keys from decoded URL.Path values, and glob stars cross slash boundaries. When open and protected namespaces share affected wildcard rules, network access alone permits unauthorized GET, PUT, or DELETE operations.
Summary
What happened
Authentication bypass in Oxyno-zeta S3-Proxy before 5.0.0 allows remote attackers to access protected S3 objects via crafted paths. The authentication middleware matches encoded RequestURI paths while the bucket handler derives object keys from decoded URL.Path values, and glob stars cross slash boundaries. When open and protected namespaces share affected wildcard rules, network access alone permits unauthorized GET, PUT, or DELETE operations.
The record
- CVE
- CVE-2026-42882
- Published
- May 11, 2026
- Updated
- May 11, 2026
- Vendor
- Oxyno-zeta
- Product
- S3-Proxy
- Classifications
- CWE-863, CWE-22, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- May 11, 2026CVE publishedPublication date reported by the CVE source.
- May 11, 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=< 5.0.0
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
- GitHub advisory integration-test proof of conceptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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