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CVE-2026-34785— Rack: Local file inclusion in `Rack::Static` via URL Prefix Matching

Quick assessment

Affected
rack rack
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Rack是Rack开源的一个模块化的Ruby web服务器界面。 Rack 2.2.23之前版本、3.1.21之前版本和3.2.6之前版本存在信息泄露漏洞，该漏洞源于Rack::Static使用简单的字符串前缀检查来确定是否应将请求作为静态文件提供，可能导致信息泄露。

CVSS 7.5 · High EPSS 0.52% · P42

Possible ATT&CK Techniques 1 AI

T1005 · Data from Local System

Affected Version Matrix 3

VendorProduct Version RangeStatus
rack rack < 2.2.23 affected
>= 3.0.0.beta1, < 3.1.21 affected
>= 3.2.0, < 3.2.6 affected
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I. Basic Information for CVE-2026-34785

Vulnerability Information
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Vulnerability Title
Rack: Local file inclusion in `Rack::Static` via URL Prefix Matching
Source: CVE Program / CVE List V5
Vulnerability Description
Rack is a modular Ruby web server interface. Prior to versions 2.2.23, 3.1.21, and 3.2.6, Rack::Static determines whether a request should be served as a static file using a simple string prefix check. When configured with URL prefixes such as "/css", it matches any request path that begins with that string, including unrelated paths such as "/css-config.env" or "/css-backup.sql". As a result, files under the static root whose names merely share the configured prefix may be served unintentionally, leading to information disclosure. This issue has been patched in versions 2.2.23, 3.1.21, and 3.2.6.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
部分比较
Source: CVE Program / CVE List V5
Vulnerability Title
Rack 信息泄露漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Rack是Rack开源的一个模块化的Ruby web服务器界面。 Rack 2.2.23之前版本、3.1.21之前版本和3.2.6之前版本存在信息泄露漏洞，该漏洞源于Rack::Static使用简单的字符串前缀检查来确定是否应将请求作为静态文件提供，可能导致信息泄露。
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

Vendor Product Affected Versions CPE Subscribe
rack rack < 2.2.23 -

II. Public POCs for CVE-2026-34785

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III. Intelligence Information for CVE-2026-34785

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Vendor Advisories for CVE-2026-34785 (1)

Same Patch Batch · rack · 2026-04-02 · 13 CVEs total

CVE-2026-34827 7.5 HIGH Rack: Algorithmic-Complexity DoS in Rack::Multipart::Parser
CVE-2026-34829 7.5 HIGH Rack: Denial of Service via Unbounded Multipart File Upload Without Content-Length
CVE-2026-34830 5.9 MEDIUM Rack: Rack::Sendfile regex injection via HTTP_X_ACCEL_MAPPING header allows arbitrary file
CVE-2026-34826 5.3 MEDIUM Rack: Unbounded Range Count in get_byte_ranges Enables DoS
CVE-2026-34786 5.3 MEDIUM Rack: Rack::Static header_rules bypass via URL-encoded paths
CVE-2026-34763 5.3 MEDIUM Rack: Rack::Directory info disclosure and DoS via unescaped regex interpolation
CVE-2026-34230 5.3 MEDIUM Rack: Quadratic complexity in Rack::Utils.select_best_encoding via wildcard Accept-Encodin
CVE-2026-26962 4.8 MEDIUM Rack: Header injection in multipart requests
CVE-2026-32762 4.8 MEDIUM Rack: Forwarded Header semicolon injection enables Host and Scheme spoofing
CVE-2026-34835 4.8 MEDIUM Rack: `Rack::Request` accepts invalid Host characters, enabling host allowlist bypass.
CVE-2026-34831 4.8 MEDIUM Rack: Content-Length mismatch in Rack::Files error responses
CVE-2026-26961 3.7 LOW Rack: Multipart Boundary Parsing Ambiguity allowing WAF Bypass

IV. Related Vulnerabilities

Same product: rack
Same vendor: rack
Same weakness: CWE-187

V. Comments for CVE-2026-34785

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