Vulnerability-Lookup

UBUNTU-CVE-2026-30852 (CVE-2026-30852)

Vulnerability from osv_ubuntu – Published: 2026-03-07 17:15 – Updated: 2026-07-02 16:12 – Source website

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

URL

Type

	https://ubuntu.com/security/CVE-2026-30852	REPORT
	https://www.cve.org/CVERecord?id=CVE-2026-30852	REPORT
	https://github.com/caddyserver/caddy/security/adv…	REPORT
	https://github.com/caddyserver/caddy/pull/5408	REPORT
	https://github.com/caddyserver/caddy/releases/tag…	REPORT

JSON

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"
  ]
}

CVE-2026-30852 (GCVE-0-2026-30852)

Vulnerability from cvelistv5 – Published: 2026-03-07 16:28 – Updated: 2026-03-09 18:24

Title

Caddy: vars_regexp double-expands user input, leaking env vars and files

Summary

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

SSVC

Exploitation: poc Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-03-09 18:19 UTC

CWE

CWE-200 - Exposure of Sensitive Information to an Unauthorized Actor
CWE-74 - Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')

Assigner

GitHub_M mitre root

References

3 references

URL	Tags
https://github.com/caddyserver/caddy/security/adv…	x_refsource_CONFIRM
https://github.com/caddyserver/caddy/pull/5408	x_refsource_MISC
https://github.com/caddyserver/caddy/releases/tag…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
caddyserver	caddy	Affected: >= 2.7.5, < 2.11.2

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-30852",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-03-09T18:19:34.437219Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-03-09T18:24:55.495Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "caddy",
          "vendor": "caddyserver",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 2.7.5, \u003c 2.11.2"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "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."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "attackComplexity": "LOW",
            "attackRequirements": "NONE",
            "attackVector": "NETWORK",
            "baseScore": 5.5,
            "baseSeverity": "MEDIUM",
            "privilegesRequired": "NONE",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "vectorString": "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",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "LOW",
            "vulnIntegrityImpact": "NONE"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-200",
              "description": "CWE-200: Exposure of Sensitive Information to an Unauthorized Actor",
              "lang": "en",
              "type": "CWE"
            }
          ]
        },
        {
          "descriptions": [
            {
              "cweId": "CWE-74",
              "description": "CWE-74: Improper Neutralization of Special Elements in Output Used by a Downstream Component (\u0027Injection\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-03-07T16:28:26.894Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/caddyserver/caddy/security/advisories/GHSA-m2w3-8f23-hxxf",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/caddyserver/caddy/security/advisories/GHSA-m2w3-8f23-hxxf"
        },
        {
          "name": "https://github.com/caddyserver/caddy/pull/5408",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/caddyserver/caddy/pull/5408"
        },
        {
          "name": "https://github.com/caddyserver/caddy/releases/tag/v2.11.2",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/caddyserver/caddy/releases/tag/v2.11.2"
        }
      ],
      "source": {
        "advisory": "GHSA-m2w3-8f23-hxxf",
        "discovery": "UNKNOWN"
      },
      "title": "Caddy: vars_regexp double-expands user input, leaking env vars and files"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-30852",
    "datePublished": "2026-03-07T16:28:26.894Z",
    "dateReserved": "2026-03-05T21:27:35.341Z",
    "dateUpdated": "2026-03-09T18:24:55.495Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

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UBUNTU-CVE-2026-30852 (CVE-2026-30852)

CVE-2026-30852 (GCVE-0-2026-30852)

Tags

Sightings

Nomenclature

Related by attack behaviour