Bug 2491896 (CVE-2026-45135)

Summary:	CVE-2026-45135 caddy: github.com/caddyserver/caddy/v2: Caddy: Remote Code Execution via Unsafe Unicode Handling in FastCGI
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security <prodsec-ir-bot>
Status:	NEW ---	QA Contact:
Severity:	high	Docs Contact:
Priority:	high
Version:	unspecified	CC:	abuckta, aprice, bsquizza, cmah, cmitchel, crizzo, dkuc, elicohen, eshamard, gtanzill, jbuscemi, jdobes, jmitchel, jsamir, jsherril, jvasik, kaycoth, kgaikwad, kshier, mstipich, oezr, orabin, rblanco, rexwhite, rochandr, stcannon, sthirugn, teagle, yguenane
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	---
Doc Text:	A flaw was found in Caddy. This vulnerability stems from unsafe handling of Unicode characters within the FastCGI component, specifically when processing request paths containing non-ASCII bytes. An attacker capable of placing content into files served via FastCGI can exploit this by crafting a malicious URL. This can mislead Caddy into executing non-script files as scripts, potentially leading to remote code execution.	Story Points:	---
Clone Of:		Environment:
Last Closed:		Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-06-23 19:01:53 UTC

Caddy is an extensible server platform that uses TLS by default. From 2.7.0 until 2.11.3, the FastCGI transport's splitPos() in modules/caddyhttp/reverseproxy/fastcgi/fastcgi.go misuses golang.org/x/text/search with search.IgnoreCase when the request path contains a non-ASCII byte. Two distinct flaws in that fallback let an attacker mislead Caddy's FastCGI splitting into treating a non-.php (or other configured split_path extension) file as a script. In any deployment where the attacker can place content into a file served via FastCGI (uploads, file storage, etc.), this can be escalated to remote code execution by crafting a URL whose path triggers either flaw. This vulnerability is fixed in 2.11.3.