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Caddy: Windows `file_server` path authorization bypass via encoded backslash

Type: advisorySources: OSV

Caddy is an extensible server platform that uses TLS by default. Prior to 2.11.4, on Windows, Caddy path matchers treat /private\secret.txt as outside /private/*, but file_server later resolves the same request path as private\secret.txt on disk. An unauthenticated remote client can bypass Caddy path-scoped auth/deny routes protecting /private/*. This vulnerability is fixed in 2.11.4.

Products
Not specified
Affected versions
Not specified
Fixed versions
Not specified
CVEs
CVE-2026-52844
Confirmed fixed CVEs
Not specified
Updated in this feed
3 Nov 2026, 02:51 UTC · Revision 1

Source evidence

Caddy: Windows `file_server` path authorization bypass via encoded backslash

core-osv · Original source

Published 23 Jun 2026, 17:50 UTC

Caddy is an extensible server platform that uses TLS by default. Prior to 2.11.4, on Windows, Caddy path matchers treat /private\secret.txt as outside /private/*, but file_server later resolves the same request path as private\secret.txt on disk. An unauthenticated remote client can bypass Caddy path-scoped auth/deny routes protecting /private/*. This vulnerability is fixed in 2.11.4.

osv:CVE-2026-52844
Complete source record
{
  "id": "59c69b13c11ee50f6c383503feea91dda8a9d5d32234d7e6b4185149c0b2b721",
  "url": "https://osv.dev/vulnerability/CVE-2026-52844",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Caddy: Windows `file_server` path authorization bypass via encoded backslash",
    "summary": "Caddy is an extensible server platform that uses TLS by default. Prior to 2.11.4, on Windows, Caddy path matchers treat /private\\secret.txt as outside /private/*, but file_server later resolves the same request path as private\\secret.txt on disk. An unauthenticated remote client can bypass Caddy path-scoped auth/deny routes protecting /private/*. This vulnerability is fixed in 2.11.4.",
    "evidence": "osv:CVE-2026-52844",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-52844",
      "aliases": [
        "CVE-2026-52844",
        "GHSA-qrp7-cvwr-j2c6",
        "GO-2026-5595"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/caddyserver/caddy",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "e2eee6a7fce366321294c9c2a79f3146891dcbdf"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "2.11.4"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "cpe": "cpe:2.3:a:caddyserver:caddy:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "2.11.4"
                      }
                    ],
                    "source": "CPE_RANGE"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v2.11.3",
            "v2.11.2",
            "v2.11.1",
            "v2.11.0",
            "v2.11.0-beta.2",
            "v2.11.0-beta.1",
            "v2.10.2",
            "v2.10.1",
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            "v2.9.0-beta.2",
            "v2.9.0-beta.1",
            "v2.8.4",
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            "v2.8.2",
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            "v2.8.0-rc.1",
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            "v2.7.5",
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            "v2.7.3",
            "v2.7.2",
            "v2.7.1",
            "v2.7.0",
            "v2.7.0-beta.2",
            "v2.7.0-beta.1",
            "v2.6.4",
            "v2.6.3",
            "v2.6.2",
            "v2.6.1",
            "v2.6.0",
            "v2.6.0-beta.5",
            "v2.6.0-beta.4",
            "v2.6.0-beta.3",
            "v2.6.0-beta.2",
            "v2.6.0-beta.1",
            "v2.5.2",
            "v2.5.1",
            "v2.5.0",
            "v2.5.0-rc.1",
            "v2.5.0-beta.1",
            "v2.4.6",
            "v2.4.5",
            "v2.4.4",
            "v2.4.3",
            "v2.4.2",
            "v2.4.1",
            "v2.4.0",
            "v2.4.0-rc.1",
            "v2.4.0-beta.2",
            "v2.4.0-beta.1",
            "v2.3.0-rc.2",
            "v2.3.0",
            "v2.3.0-rc.1",
            "v2.3.0-beta.1",
            "v2.2.3",
            "v2.2.1",
            "v2.2.0",
            "v2.2.0-rc.3",
            "v2.2.0-rc.2",
            "v2.2.0-rc.1",
            "v2.1.1",
            "v2.1.0",
            "v2.1.0-beta.2",
            "v2.1.0-beta.1",
            "v2.0.0",
            "v2.0.0-rc.3",
            "v2.0.0-rc.2",
            "v2.0.0-rc.1",
            "v2.0.0-beta.20",
            "v2.0.0-beta.19",
            "v2.0.0-beta.18",
            "v2.0.0-beta.17",
            "v2.0.0-beta.16",
            "v2.0.0-beta.15",
            "v2.0.0-beta.14",
            "v2.0.0-beta.13",
            "v2.0.0-beta12",
            "v2.0.0-beta11",
            "v2.0.0-beta10",
            "v2.0.0-beta9",
            "v2.0.0-beta8",
            "v2.0.0-beta7",
            "v2.0.0-beta6",
            "v2.0.0-beta5",
            "v2.0.0-beta4",
            "v2.0.0-beta3",
            "v2.0.0-beta2",
            "v2.0.0-beta1"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-52844.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:25.166386615Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/52xxx/CVE-2026-52844.json",
        "https://github.com/caddyserver/caddy/security/advisories/GHSA-qrp7-cvwr-j2c6",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-52844"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-22",
          "CWE-284"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/52xxx/CVE-2026-52844.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-52844",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 492042,
  "published_at": "2026-06-23T17:50:42.386+00:00"
}