{"id":"CVE-2026-42882","revision":"71c5aa1331fd4fffbf12c52863942d1b","records":[{"revision":"71c5aa1331fd4fffbf12c52863942d1b","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-42882","aliases":[],"title":"oxyno-zeta/s3-proxy: Security Issues in Resource Path Matching","description":"oxyno-zeta/s3-proxy is an aws s3 proxy written in go. Prior to 5.0.0, s3-proxy contains an authentication bypass caused by inconsistent URL path interpretation between the authentication middleware and the bucket handler. The authentication middleware evaluates resource path patterns against the percent-encoded request URI (r.URL.RequestURI()), while the bucket handler constructs S3 object keys from the decoded path (r.URL.Path). This mismatch, combined with the glob library being invoked without a path separator (causing * to match across / boundaries), allows unauthenticated attackers to write to, read from, or delete objects in protected S3 namespaces. Exploitation is possible via three techniques: (1) using * patterns\nthat match across path separators to reach protected routes via path traversal (e.g., /open/foo/drafts/../restricted/), (2) using percent-encoded slashes (%2F) to collapse multiple path segments into a single token at the auth layer while the decoded form resolves to a protected namespace at the storage layer, and (3) using dot-dot segments (../) under ** prefix patterns, where the raw path matches an open route while Go's URL parser resolves the traversal to a protected path before the bucket handler runs. An unauthenticated attacker with network access can perform unauthorized PUT, GET, or DELETE operations on objects in authentication-protected S3 namespaces. This vulnerability is fixed in 5.0.0.","state":0,"publishedAt":"2026-05-11T19:26:44.897+00:00","modifiedAt":"2026-05-13T14:40:36.658+00:00","affected":[{"ecosystem":"Vendor product","name":"s3-proxy","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"oxyno-zeta\",\n                    \"product\": \"s3-proxy\",\n                    \"versions\": [\n                        {\n                            \"version\": \"< 5.0.0\",\n                            \"status\": \"affected\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L","score":9.4,"severity":"CRITICAL"}],"references":["https://github.com/oxyno-zeta/s3-proxy/security/advisories/GHSA-rfgq-wgg8-662p","https://github.com/oxyno-zeta/s3-proxy/commit/1320e4abd46ad18c2851fedde50dbb79df8b7a51","https://github.com/oxyno-zeta/s3-proxy/commit/af5ff57d8c6022459495b8fb50130073bca7b48a"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-42882","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-42882","identifiers":["CVE-2026-42882"]},"retained":false,"historicalAffected":[]}],"coverage":[]}