Improper Handling of Unicode Encoding in Caddy - CVE-2026-45135
Published: November 9, 2026
Vulnerability identifier: #VU163178
CSH Severity: High
CVSS v4: 9.2 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-45135
CWE-ID: CWE-176
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows an unauthenticated remote attacker to execute arbitrary code in a FastCGI upstream through non-PHP files.
The vulnerability exists due to unsafe Unicode handling in Caddy's FastCGI path splitting when non-ASCII request paths are matched against configured script extensions. An unauthenticated remote attacker can place executable content in a served file with a specially crafted non-ASCII filename and request a crafted URL to have that file treated as a script.
Affected software
Caddy
How to mitigate CVE-2026-45135
Install security update from vendor's website.
Caddy - update to 2.11.3