CVE-2026-30852

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.

CVSS v3 7.5 HIGH

7.5^/10

CVSS v3 : HIGH

Vector :

Exploitability : 3.9 / Impact : 3.6

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact NONE

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://github.com/caddyserver/caddy/pull/5408	Issue Tracking Patch
https://github.com/caddyserver/caddy/releases/tag/v2.11.2	Product Release Notes
https://github.com/caddyserver/caddy/security/advisories/GHSA-m2w3-8f23-hxxf	Exploit Mitigation Vendor Advisory

Configurations

Configuration 1 (hide)

cpe:2.3:a:caddyserver:caddy:*:*:*:*:*:*:*:*

History

No history.

Information

Published : 2026-03-07 17:15

Updated : 2026-03-11 13:01

NVD link : CVE-2026-30852

Mitre link : CVE-2026-30852

CVE.ORG link : CVE-2026-30852

JSON object : View

Products Affected

caddyserver

caddy

CWE

CWE-74

Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')

CWE-200

Exposure of Sensitive Information to an Unauthorized Actor

{"id": "CVE-2026-30852", "cveTags": [], "metrics": {"cvssMetricV31": [{"type": "Primary", "source": "nvd@nist.gov", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 7.5, "attackVector": "NETWORK", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "NONE", "privilegesRequired": "NONE", "confidentialityImpact": "HIGH"}, "impactScore": 3.6, "exploitabilityScore": 3.9}], "cvssMetricV40": [{"type": "Secondary", "source": "security-advisories@github.com", "cvssData": {"Safety": "NOT_DEFINED", "version": "4.0", "Recovery": "NOT_DEFINED", "baseScore": 5.5, "Automatable": "NOT_DEFINED", "attackVector": "NETWORK", "baseSeverity": "MEDIUM", "valueDensity": "NOT_DEFINED", "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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "exploitMaturity": "PROOF_OF_CONCEPT", "providerUrgency": "NOT_DEFINED", "userInteraction": "NONE", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "subIntegrityImpact": "NONE", "vulnIntegrityImpact": "NONE", "integrityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "vulnAvailabilityImpact": "NONE", "availabilityRequirement": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "subConfidentialityImpact": "NONE", "vulnConfidentialityImpact": "LOW", "confidentialityRequirement": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED"}}]}, "published": "2026-03-07T17:15:52.733", "references": [{"url": "https://github.com/caddyserver/caddy/pull/5408", "tags": ["Issue Tracking", "Patch"], "source": "security-advisories@github.com"}, {"url": "https://github.com/caddyserver/caddy/releases/tag/v2.11.2", "tags": ["Product", "Release Notes"], "source": "security-advisories@github.com"}, {"url": "https://github.com/caddyserver/caddy/security/advisories/GHSA-m2w3-8f23-hxxf", "tags": ["Exploit", "Mitigation", "Vendor Advisory"], "source": "security-advisories@github.com"}], "vulnStatus": "Analyzed", "weaknesses": [{"type": "Primary", "source": "security-advisories@github.com", "description": [{"lang": "en", "value": "CWE-74"}, {"lang": "en", "value": "CWE-200"}]}], "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."}, {"lang": "es", "value": "Caddy es una plataforma de servidor extensible que usa TLS por defecto. Desde la versi\u00f3n 2.7.5 hasta antes de la versi\u00f3n 2.11.2, el comparador vars_regexp en vars.go:337 expande doblemente la entrada controlada por el usuario a trav\u00e9s del reemplazador de Caddy. Cuando vars_regexp coincide con un marcador de posici\u00f3n como {http.request.header.X-Input}, el valor del encabezado se resuelve una vez (esperado), y luego se pasa por repl.ReplaceAll() de nuevo (el error). Esto significa que un atacante puede colocar {env.DATABASE_URL} o {file./etc /passwd} en un encabezado de solicitud y el servidor lo evaluar\u00e1, filtrando variables de entorno, contenido de archivos e informaci\u00f3n del sistema. Este problema ha sido parcheado en la versi\u00f3n 2.11.2."}], "lastModified": "2026-03-11T13:01:46.030", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:caddyserver:caddy:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "A3772146-497E-4F88-B309-90C277081DE9", "versionEndExcluding": "2.11.2", "versionStartIncluding": "2.7.5"}], "operator": "OR"}]}], "sourceIdentifier": "security-advisories@github.com"}