Improper access control in Caddy - CVE-2026-27587
Published: April 27, 2026
Vulnerability identifier: #VU128030
CSH Severity: High
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:U/U:Amber
CVE-ID: CVE-2026-27587
CWE-ID: CWE-284
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Caddy
Affected software:
Caddy
Caddy
Detailed vulnerability description
The vulnerability allows a remote attacker to bypass path-based routing and access controls.
The vulnerability exists due to improper access control in the MatchPath path request matcher when processing request paths containing percent-escape sequences. A remote attacker can send a specially crafted request path with altered casing to bypass path-based routing and access controls.
Exploitation requires a deployment that uses path matchers with %xx patterns to protect sensitive endpoints, and the issue can lead to unauthorized access depending on upstream configuration.
How to mitigate CVE-2026-27587
Install security update from vendor's website.