CVE-2026-27587
Caddy MatchPath %xx branch skips case normalization in github.com/caddyserver/caddy/v2
9.1
CRITICAL
CVSS 3.1
EPSS 0.06%
Description
Caddy is an extensible server platform that uses TLS by default. Prior to version 2.11.1, Caddy's HTTP `path` request matcher is intended to be case-insensitive, but when the match pattern contains percent-escape sequences (`%xx`) it compares against the request's escaped path without lowercasing. An attacker can bypass path-based routing and any access controls attached to that route by changing the casing of the request path. Version 2.11.1 contains a fix for the issue.
How to fix CVE-2026-27587
To remediate CVE-2026-27587, upgrade the affected package to a fixed version below.
- —no fix listed
- —upgrade to 2.11.1 or later
- —upgrade to 2.11.1 or later
Is CVE-2026-27587 being exploited?
Low — EPSS is 0.1%, meaning exploitation activity has not been observed at scale.
Affected packages (3)
- from 0
- from 0, < 2.11.1
- from 0, < 2.11.1
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 4.0 | — | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:P |
| osv | CVSS 3.1 | CRITICAL9.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N |