{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "0"
              },
              {
                "fixed": "5.0.0"
              }
            ],
            "source": "AFFECTED_FIELD"
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "af5ff57d8c6022459495b8fb50130073bca7b48a"
            }
          ],
          "repo": "https://github.com/oxyno-zeta/s3-proxy",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-rfgq-wgg8-662p"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-22",
      "CWE-863"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42882.json"
  },
  "details": "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.",
  "id": "CVE-2026-42882",
  "modified": "2026-08-04T11:31:21.011171800Z",
  "published": "2026-05-11T19:26:44.897Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42882.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/oxyno-zeta/s3-proxy/security/advisories/GHSA-rfgq-wgg8-662p"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-42882"
    },
    {
      "type": "FIX",
      "url": "https://github.com/oxyno-zeta/s3-proxy/commit/1320e4abd46ad18c2851fedde50dbb79df8b7a51"
    },
    {
      "type": "FIX",
      "url": "https://github.com/oxyno-zeta/s3-proxy/commit/af5ff57d8c6022459495b8fb50130073bca7b48a"
    }
  ],
  "schema_version": "1.8.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L",
      "type": "CVSS_V3"
    }
  ],
  "summary": "oxyno-zeta/s3-proxy: Security Issues in Resource Path Matching"
}