Caddy
CVE-2026-27585
MEDIUM
GHSA-4xrr-hq4w-6vf4
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A05:2025 - Injection
ASVS 5.0
V2 - Validation and Business Logic Input validation, allowlisting
|
| Impact | CVSS 6.5 (MEDIUM). Attack vector: Network. Complexity: Low. Privileges required: None. User interaction: None. Public exploit/POC available. |
| Exploit ScenarioDerived | An attacker could exploit this vulnerability to bypassing path related security protections. |
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Alert meAnalysisAIv1 – Mar 12, 2026
Caddy versions prior to 2.11.1 fail to sanitize backslashes in file path matching, allowing attackers to bypass path-based security controls through specially crafted requests. The vulnerability affects systems with specific Caddy configurations and has public exploit code available. Exploitation requires network access with no authentication, resulting in limited information disclosure or modification of restricted resources.
Earlier versions of this analysis (1)
Caddy is an extensible server platform that uses TLS by default. Prior to version 2.11.1, the path sanitization routine in file matcher doesn't sanitize backslashes which can lead to bypassing path related security protections. [CVSS 6.5 MEDIUM]
RemediationAI
Monitor vendor advisories for a patch. Restrict network access to the affected service where possible.
Affected Packages
Source: OSV (Open Source Vulnerabilities)
Affects your stack
Affects 1 package in go
Checking this CVE against your own stacks and servers is part of the Basic plan and up.
Technical ContextAI · show details
Classified as CWE-20 (Improper Input Validation). Affects Caddy. Caddy is an extensible server platform that uses TLS by default. Prior to version 2.11.1, the path sanitization routine in file matcher doesn't sanitize backslashes which can lead to bypassing path related security protections. It affects users with specific Caddy and environment configurations. Version 2.11.1 fixes the issue.
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- Exploit and PoC references, threat intelligence from 22 sources
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Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/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. Prior to version 2.11.1, the path sanitization routine in file matcher doesn't sanitize backslashes which can lead to bypassing path related security protections. It affects users with specific Caddy and environment configurations. Version 2.11.1 fixes the issue.
Executive ViewAI
Organizations using Caddy should be aware of notable risk from CVE-2026-27585, a input validation vulnerability rated CVSS 6.5. Exploitation could compromise the security of affected deployments. Proof-of-concept code is publicly available. Organizations should apply vendor updates when available and monitor for exploitation.
Apply vendor patch. If patching is delayed: deploy WAF rules, restrict network access, enable logging.
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
Denial of service against HTTP/2 server implementations allows remote unauthenticated attackers to exhaust server resour
FastCGI path splitting vulnerability in Caddy before 2.11.1 allows request smuggling or path confusion when proxying to
TLS error swallowing in Caddy web server before 2.11.1 allows bypassing client certificate authentication. Errors in Cli
Host header case sensitivity bypass in Caddy before 2.11.1. Virtual host routing can be bypassed by using alternate casi
Case sensitivity bypass in Caddy web server path matching before 2.11.1. HTTP path matchers can be bypassed using altern
Caddy versions 2.10.0 through 2.11.1 fail to strip client-supplied headers in the forward_auth copy_headers directive, e
Caddy versions 2.7.5 through 2.11.1 contain a template injection vulnerability in the vars_regexp matcher that allows re
An out-of-bounds read in the rewrite function at /modules/caddyhttp/rewrite/rewrite.go in Caddy v2.5.1 allows attackers
A configuration-gated information-disclosure flaw in Caddy 2.11.3 and earlier allows an unauthenticated remote attacker
Caddy versions prior to 2.11.1 allow unauthenticated cross-origin requests to the admin API when origin enforcement is d
An issue was discovered in caddy (for TYPO3) before 7.2.10. Rated medium severity (CVSS 6.1), this vulnerability is remo
Caddy through 0.11.0 sends incorrect certificates for certain invalid requests, making it easier for attackers to enumer
Same weakness CWE-20 – Improper Input Validation
View allVendor StatusVendor
SUSE
Severity: Medium| 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 |
Exploit-DB