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Vulnerability Details :

CVE-2026-27590

Summary
Assigner-GitHub_M
Assigner Org ID-a0819718-46f1-4df5-94e2-005712e83aaa
Published At-24 Feb, 2026 | 16:33
Updated At-24 Feb, 2026 | 16:33
Rejected At-
Credits

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

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.

Vendors
-
Not available
Products
-
Metrics (CVSS)
VersionBase scoreBase severityVector
Weaknesses
Attack Patterns
Solution/Workaround
References
HyperlinkResource Type
EPSS History
Score
Latest Score
-
N/A
No data available for selected date range
Percentile
Latest Percentile
-
N/A
No data available for selected date range
Stakeholder-Specific Vulnerability Categorization (SSVC)
▼Common Vulnerabilities and Exposures (CVE)
cve.org
Assigner:GitHub_M
Assigner Org ID:a0819718-46f1-4df5-94e2-005712e83aaa
Published At:24 Feb, 2026 | 16:33
Updated At:24 Feb, 2026 | 16:33
Rejected At:
▼CVE Numbering Authority (CNA)
Caddy: Unicode case-folding length expansion causes incorrect split_path index (SCRIPT_NAME/PATH_INFO confusion) in FastCGI transport

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.

Affected Products
Vendor
caddyserver
Product
caddy
Versions
Affected
  • < 2.11.1
Problem Types
TypeCWE IDDescription
CWECWE-20CWE-20: Improper Input Validation
CWECWE-180CWE-180: Incorrect Behavior Order: Validate Before Canonicalize
Type: CWE
CWE ID: CWE-20
Description: CWE-20: Improper Input Validation
Type: CWE
CWE ID: CWE-180
Description: CWE-180: Incorrect Behavior Order: Validate Before Canonicalize
Metrics
VersionBase scoreBase severityVector
4.08.9HIGH
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
Version: 4.0
Base score: 8.9
Base severity: HIGH
Vector:
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
Metrics Other Info
Impacts
CAPEC IDDescription
Solutions

Configurations

Workarounds

Exploits

Credits

Timeline
EventDate
Replaced By

Rejected Reason

References
HyperlinkResource
https://github.com/caddyserver/caddy/security/advisories/GHSA-5r3v-vc8m-m96g
x_refsource_CONFIRM
https://github.com/php/frankenphp/security/advisories/GHSA-g966-83w7-6w38
x_refsource_MISC
https://github.com/caddyserver/caddy/releases/tag/v2.11.1
x_refsource_MISC
Hyperlink: https://github.com/caddyserver/caddy/security/advisories/GHSA-5r3v-vc8m-m96g
Resource:
x_refsource_CONFIRM
Hyperlink: https://github.com/php/frankenphp/security/advisories/GHSA-g966-83w7-6w38
Resource:
x_refsource_MISC
Hyperlink: https://github.com/caddyserver/caddy/releases/tag/v2.11.1
Resource:
x_refsource_MISC
Information is not available yet
▼National Vulnerability Database (NVD)
nvd.nist.gov
Source:security-advisories@github.com
Published At:24 Feb, 2026 | 17:29
Updated At:24 Feb, 2026 | 21:52

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.

CISA Catalog
Date AddedDue DateVulnerability NameRequired Action
N/A
Date Added: N/A
Due Date: N/A
Vulnerability Name: N/A
Required Action: N/A
Metrics
TypeVersionBase scoreBase severityVector
Secondary4.08.9HIGH
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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Type: Secondary
Version: 4.0
Base score: 8.9
Base severity: HIGH
Vector:
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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CPE Matches

Weaknesses
CWE IDTypeSource
CWE-20Primarysecurity-advisories@github.com
CWE-180Primarysecurity-advisories@github.com
CWE ID: CWE-20
Type: Primary
Source: security-advisories@github.com
CWE ID: CWE-180
Type: Primary
Source: security-advisories@github.com
Evaluator Description

Evaluator Impact

Evaluator Solution

Vendor Statements

References
HyperlinkSourceResource
https://github.com/caddyserver/caddy/releases/tag/v2.11.1security-advisories@github.com
N/A
https://github.com/caddyserver/caddy/security/advisories/GHSA-5r3v-vc8m-m96gsecurity-advisories@github.com
N/A
https://github.com/php/frankenphp/security/advisories/GHSA-g966-83w7-6w38security-advisories@github.com
N/A
Hyperlink: https://github.com/caddyserver/caddy/releases/tag/v2.11.1
Source: security-advisories@github.com
Resource: N/A
Hyperlink: https://github.com/caddyserver/caddy/security/advisories/GHSA-5r3v-vc8m-m96g
Source: security-advisories@github.com
Resource: N/A
Hyperlink: https://github.com/php/frankenphp/security/advisories/GHSA-g966-83w7-6w38
Source: security-advisories@github.com
Resource: N/A

Change History

0
Information is not available yet

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Details not found