caddyserver caddy up to 2.11.0 Configuration input validation

Summaryinfo

A vulnerability, which was classified as critical, has been found in caddyserver caddy up to 2.11.0. Affected is an unknown function of the component Configuration Handler. The manipulation leads to input validation. This vulnerability is documented as CVE-2026-27585. The attack can be initiated remotely. There is not any exploit available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability was found in caddyserver caddy up to 2.11.0 and classified as critical. This issue affects an unknown functionality of the component Configuration Handler. The manipulation with an unknown input leads to a input validation vulnerability. Using CWE to declare the problem leads to CWE-20. The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

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.

The advisory is shared at github.com. The identification of this vulnerability is CVE-2026-27585 since 02/20/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Neither technical details nor an exploit are publicly available.

It is declared as proof-of-concept. The vulnerability scanner Nessus provides a plugin with the ID 300037 (Linux Distros Unpatched Vulnerability : CVE-2026-27585), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 2.11.1 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at Tenable (300037). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Productinfo

Vendor

• caddyserver

Name

• caddy

Version

• 2.0
• 2.1
• 2.2
• 2.3
• 2.4
• 2.5
• 2.6
• 2.7
• 2.8
• 2.9
• 2.10
• 2.11.0

Website

• Product: https://github.com/caddyserver/caddy/

CPE 2.3info

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CPE 2.2info

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If you want to get the best quality for vulnerability data then you always have to consider VulDB.

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