Goal Reached Thanks to every supporter — we hit 100%!

Goal: 1000 CNY · Raised: 1336 CNY

100%
Buy Us a Coffee

CVE-2026-27590— Caddy: Unicode case-folding length expansion causes incorrect split_path index (SCRIPT_NAME/PATH_INFO confusion) in FastCGI transport

AI Predicted 9.0 Difficulty: Easy EPSS 0.54% · P42

Possible ATT&CK Techniques 1AI

T1190 · Exploit Public-Facing Application
Get alerts for future matching vulnerabilitiesLog in to subscribe

I. Basic Information for CVE-2026-27590

Vulnerability Information
Have questions about the vulnerability? See if Shenlong's analysis helps!
View Shenlong Deep Dive ↗

Although we use advanced large model technology, its output may still contain inaccurate or outdated information.Shenlong tries to ensure data accuracy, but please verify and judge based on the actual situation.

Vulnerability Title
Caddy: Unicode case-folding length expansion causes incorrect split_path index (SCRIPT_NAME/PATH_INFO confusion) in FastCGI transport
Source: CVE Program / CVE List V5
Vulnerability Description
Caddy is an extensible server platform that uses TLS by default. Prior to version 2.11.1, Caddy's FastCGI path splitting logic computes the split index on a lowercased copy of the request path and then uses that byte index to slice the original path. This is unsafe for Unicode because `strings.ToLower()` can change UTF-8 byte length for some characters. As a result, Caddy can derive an incorrect `SCRIPT_NAME`/`SCRIPT_FILENAME` and `PATH_INFO`, potentially causing a request that contains `.php` to execute a different on-disk file than intended (path confusion). In setups where an attacker can control file contents (e.g., upload features), this can lead to unintended PHP execution of non-.php files (potential RCE depending on deployment). Version 2.11.1 fixes the issue.
Source: CVE Program / CVE List V5
CVSS Information
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
Source: CVE Program / CVE List V5
Vulnerability Type
输入验证不恰当
Source: CVE Program / CVE List V5
Vulnerability Title
Caddy 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Caddy是Caddy公司的一款开源、跨平台的HTTP/Web服务器。 Caddy 2.11.1之前版本存在安全漏洞，该漏洞源于FastCGI路径分割逻辑在处理Unicode时存在缺陷，可能导致路径混淆和潜在的非.php文件执行。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

VendorProductAffected VersionsCPESubscribe
caddyservercaddy < 2.11.1 -

II. Public POCs for CVE-2026-27590

#POC DescriptionSource LinkShenlong Link
AI-Generated POCPremium

No public POC found.

Login to generate AI POC

III. Intelligence Information for CVE-2026-27590

请登录查看更多情报信息。

Vendor Advisories for CVE-2026-27590 (1)

Vendor Pages for CVE-2026-27590 (1)

Same Patch Batch · caddyserver · 2026-02-24 · 6 CVEs total

CVE-2026-27585Caddy's improper sanitization of glob characters in file matcher may lead to bypassing sec
CVE-2026-27586Caddy's mTLS client authentication silently fails open when CA certificate file is missing
CVE-2026-27587Caddy: MatchPath %xx (escaped-path) branch skips case normalization, enabling path-based r
CVE-2026-27588Caddy: MatchHost becomes case-sensitive for large host lists (>100), enabling host-based r
CVE-2026-27589Caddy vulnerable to cross-origin config application via local admin API /load (caddy)

IV. Related Vulnerabilities

Same product: caddy
Same vendor: caddyserver
Same weakness: CWE-20

V. Comments for CVE-2026-27590

No comments yet

Leave a comment