ubuntu-cve-2026-30852
Vulnerability from osv_ubuntu
Published
2026-03-07 17:15
Modified
2026-07-02 16:12
Summary
Details

Caddy is an extensible server platform that uses TLS by default. From version 2.7.5 to before version 2.11.2, the vars_regexp matcher in vars.go:337 double-expands user-controlled input through the Caddy replacer. When vars_regexp matches against a placeholder like {http.request.header.X-Input}, the header value gets resolved once (expected), then passed through repl.ReplaceAll() again (the bug). This means an attacker can put {env.DATABASE_URL} or {file./etc/passwd} in a request header and the server will evaluate it, leaking environment variables, file contents, and system info. This issue has been patched in version 2.11.2.

Severity
5.5 (Medium)
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:P
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
N/A (UNKNOWN)
medium
References
To clipboard 

{
  "affected": [
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "caddy",
            "binary_version": "2.6.2-6ubuntu0.24.04.3+esm2"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:24.04:LTS",
        "name": "caddy",
        "purl": "pkg:deb/ubuntu/caddy@2.6.2-6ubuntu0.24.04.3+esm2?arch=source\u0026distro=esm-apps/noble"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.6.2-6",
        "2.6.2-6ubuntu0.24.04.1",
        "2.6.2-6ubuntu0.24.04.2",
        "2.6.2-6ubuntu0.24.04.2+esm1",
        "2.6.2-6ubuntu0.24.04.3",
        "2.6.2-6ubuntu0.24.04.3+esm1",
        "2.6.2-6ubuntu0.24.04.3+esm2"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "caddy",
            "binary_version": "2.6.2-12"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:25.10",
        "name": "caddy",
        "purl": "pkg:deb/ubuntu/caddy@2.6.2-12?arch=source\u0026distro=questing"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.6.2-9",
        "2.6.2-11",
        "2.6.2-12"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "caddy",
            "binary_version": "2.6.2-14ubuntu0.26.04.1~esm1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:26.04:LTS",
        "name": "caddy",
        "purl": "pkg:deb/ubuntu/caddy@2.6.2-14ubuntu0.26.04.1~esm1?arch=source\u0026distro=esm-apps/resolute"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.6.2-12",
        "2.6.2-14",
        "2.6.2-14ubuntu0.26.04.1~esm1"
      ]
    }
  ],
  "aliases": [],
  "details": "Caddy is an extensible server platform that uses TLS by default. From version 2.7.5 to before version 2.11.2, the vars_regexp matcher in vars.go:337 double-expands user-controlled input through the Caddy replacer. When vars_regexp matches against a placeholder like {http.request.header.X-Input}, the header value gets resolved once (expected), then passed through repl.ReplaceAll() again (the bug). This means an attacker can put {env.DATABASE_URL} or {file./etc/passwd} in a request header and the server will evaluate it, leaking environment variables, file contents, and system info. This issue has been patched in version 2.11.2.",
  "id": "UBUNTU-CVE-2026-30852",
  "modified": "2026-07-02T16:12:00Z",
  "published": "2026-03-07T17:15:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2026-30852"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-30852"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/caddyserver/caddy/security/advisories/GHSA-m2w3-8f23-hxxf"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/caddyserver/caddy/pull/5408"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/caddyserver/caddy/releases/tag/v2.11.2"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:P",
      "type": "CVSS_V4"
    },
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
      "type": "CVSS_V3"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2026-30852"
  ]
}



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