Caddy's improper sanitization of glob characters in file matcher may lead to bypassing security protections
Priority MEDIUM 64CWE-20Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Attack requirements
- Present
- Impact type
- —
- Confidentiality · integrity · availability
- None · High · None
- Fix status
- Fixed
Attack profile from CVSS 4.0 · CNA. Fix status from CNA and GitHub.
Summary
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.
Why it matters now
Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00367 30th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Fixed caddy (caddyserver): 2.11.1github.com/caddyserver/caddy/v2 (Go): 2.11.1
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- Poc
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| caddyserver | caddy | before 2.11.1 | 2.11.1 | Patch available | CNA |
| — | github.com/caddyserver/caddy/v2 (Go) | before 2.11.1 | 2.11.1 | Patch available | GHSA-4xrr-hq4w-6vf4 |
- caddy Vendorcaddyserver Affected before 2.11.1 Fixed in 2.11.1 Patch available CNA
- github.com/caddyserver/caddy/v2 (Go) Vendor— Affected before 2.11.1 Fixed in 2.11.1 Patch available GHSA-4xrr-hq4w-6vf4
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:caddyserver:caddy:*:*:*:*:*:*:*:* | before 2.11.1 | Vulnerable | caddyserver |
- cpe:2.3:a:caddyserver:caddy:*:*:*:*:*:*:*:* Versions before 2.11.1 Vulnerable ·caddyserver
Remediation
- Fix · CNA caddy (caddyserver) Fixed in 2.11.1
- Fix · GHSA-4xrr-hq4w-6vf4 github.com/caddyserver/caddy/v2 (Go) Fixed in 2.11.1 Advisory →
Vendor assessments
Timeline
- 2026-10-02 Threatist record created from CVE-2026-27585
- 2026-10-03 Alias added: GHSA-4xrr-hq4w-6vf4
References
Other 6
- https://github.com/caddyserver/caddy/blob/68d50020eef0d4c3398b878f17c8092ca5b58ca0/modules/caddyhttp/fileserver/matcher.go#L361
- https://github.com/caddyserver/caddy/blob/68d50020eef0d4c3398b878f17c8092ca5b58ca0/modules/caddyhttp/fileserver/matcher.go#L398
- https://github.com/caddyserver/caddy/releases/tag/v2.11.1
- https://caddyserver.com/docs/caddyfile/directives#directive-order
- https://github.com/caddyserver/caddy
- https://pkg.go.dev/vuln/GO-2026-4535
More caddyserver Caddy vulnerabilities
- TI-2023-23979 The HTTP/2 protocol allows a denial of service (server resource consumption) because… KEVCVSS 3.1HIGH 7.5
- TI-2026-21978 Improper input validation in caddyserver caddy CVSS 4.0HIGH 8.9
- TI-2026-21974 Caddy's mTLS client authentication silently fails open when CA certificate file is missing or malformed CVSS 4.0HIGH 8.8
- TI-2026-23680 Improper authentication in caddyserver caddy CVSS 3.1HIGH 8.8
- TI-2026-21976 Caddy: MatchHost becomes case-sensitive for large host lists (>100), enabling host-based route/auth bypass CVSS 4.0HIGH 7.7
- TI-2026-21975 Caddy: MatchPath %xx (escaped-path) branch skips case normalization, enabling path-based route/auth bypass CVSS 4.0HIGH 7.7
Sources
- CVE-2026-27585 · CVE Program
- CVE-2026-27585 · NVD
- FIRST EPSS
- GHSA-4xrr-hq4w-6vf4 · GitHub Advisory Database · CC BY 4.0
- CVE-2026-27585 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences