CVE-2026-27590Public exploitNetwork attack vector

Remote code execution via Unicode path confusion

Published Feb 24, 2026 · Updated Feb 24, 2026

Path confusion in Caddy before 2.11.1 allows remote attackers to execute attacker-controlled non-PHP files through crafted URLs. FastCGI Transport.splitPos lowercases the request path before locating .php, then buildEnv slices the original UTF-8 path with that shifted byte index, missetting SCRIPT_FILENAME and PATH_INFO. Code execution requires a FastCGI PHP deployment and an attacker-controlled file that the confused script path can resolve.

CVSS severity9.8
Critical
EPSS probability0.54%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Path confusion in Caddy before 2.11.1 allows remote attackers to execute attacker-controlled non-PHP files through crafted URLs. FastCGI Transport.splitPos lowercases the request path before locating .php, then buildEnv slices the original UTF-8 path with that shifted byte index, missetting SCRIPT_FILENAME and PATH_INFO. Code execution requires a FastCGI PHP deployment and an attacker-controlled file that the confused script path can resolve.

The record

CVE
CVE-2026-27590
Published
Feb 24, 2026
Updated
Feb 24, 2026
Vendor
Caddy
Product
Caddy
Classifications
CWE-180, CWE-20, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 24, 2026CVE publishedPublication date reported by the CVE source.
  2. Feb 24, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 2.11.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Caddy · Caddyversion=< 2.11.1

Published CVSS scores

8.9GitHub, Inc.CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P
9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-180Incorrect Behavior Order Validate Before Canonicalize
CWE-20Improper Input Validation
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo