Caddy
CVE-2026-30852
HIGH
GHSA-m2w3-8f23-hxxf
Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain
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AccessCraft HTTP request with placeholder syntax in header
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Exploitvars_regexp matcher processes header value
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ExecutionReplacer double-expands sensitive placeholders
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ImpactLeak environment variables or file contents
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A05:2025 - Injection
ASVS 5.0
V1 - Encoding and Sanitization Input neutralization, injection prevention
|
| Exploitation Conditions | Caddy versions 2.7.5 to before 2.11.2 with vars_regexp matcher enabled in route configuration. No special conditions — remote unauthenticated exploitation against default configurations requiring only HTTP access to routes using vars_regexp matcher. |
| Impact | CVSS 7.5 (HIGH). Attack vector: Network. Complexity: Low. Privileges required: None. User interaction: None. Public exploit/POC available. |
| Exploit ScenarioDerived | An attacker could exploit this vulnerability to compromise the affected system. |
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Alert meAnalysisAIv1 – Mar 12, 2026
Caddy versions 2.7.5 through 2.11.1 contain a template injection vulnerability in the vars_regexp matcher that allows remote attackers to perform double variable expansion on user-controlled input, enabling disclosure of environment variables and file contents. By injecting placeholders like {env.DATABASE_URL} or {file./etc/passwd} into request headers, an unauthenticated attacker can leak sensitive system information. Public exploit code exists for this vulnerability, which is fixed in version 2.11.2.
Earlier versions of this analysis (1)
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. [CVSS 7.5 HIGH]
RemediationAI
A vendor patch is available — apply it immediately. Fixed in version 2.11.2.. Restrict network access to the affected service where possible.
Affected Packages
Source: OSV (Open Source Vulnerabilities)
Affects your stack
Affects 2 packages in go
Checking this CVE against your own stacks and servers is part of the Basic plan and up.
Technical ContextAI · show details
Affects Caddy. 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
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Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Primary rating from GitHub Advisory.
CVSS VectorGitHub Advisory
Lifecycle Timeline
3DescriptionGitHub Advisory
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.
Executive ViewAI
Caddy web server versions 2.7.5 through 2.11.1 contain a high-severity vulnerability allowing attackers to bypass security controls through input manipulation. Organizations running affected Caddy instances face potential unauthorized access and data exposure risks.
Apply vendor patch.
Threat Intelligence Overview
NVD
CVE.org
EPSS
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Affected Products (CPE)GitHub Advisory
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Vendor StatusVendor
SUSE
Severity: High| Product | Status |
|---|---|
| openSUSE Leap 15.6 | Fixed |
| SUSE Linux Enterprise Module for Package Hub 15 SP5 | Fixed |
| SUSE Linux Enterprise Module for Package Hub 15 SP6 | Fixed |
| openSUSE Leap 15.5 | Fixed |
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