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CVE-2026-34763— Rack: Rack::Directory info disclosure and DoS via unescaped regex interpolation

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之前版本存在安全漏洞，该漏洞源于Rack::Directory将配置的根路径直接插入正则表达式，可能导致生成的目录列表在HTML输出中暴露完整文件系统路径。

CVSS 5.3 · Medium EPSS 0.33% · P24

Possible ATT&CK Techniques 1 AI

T1083 · File and Directory Discovery
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I. Basic Information for CVE-2026-34763

Vulnerability Information
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Vulnerability Title
Rack: Rack::Directory info disclosure and DoS via unescaped regex interpolation
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::Directory interpolates the configured root path directly into a regular expression when deriving the displayed directory path. If root contains regex metacharacters such as +, *, or ., the prefix stripping can fail and the generated directory listing may expose the full filesystem path in the HTML output. 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:L/I:N/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
宽松定义的正则表达式
Source: CVE Program / CVE List V5
Vulnerability Title
Rack 安全漏洞
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之前版本存在安全漏洞，该漏洞源于Rack::Directory将配置的根路径直接插入正则表达式，可能导致生成的目录列表在HTML输出中暴露完整文件系统路径。
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-2026-34763

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III. Intelligence Information for CVE-2026-34763

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Vendor Advisories for CVE-2026-34763 (1)

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

CVE-2026-34785 7.5 HIGH Rack: Local file inclusion in `Rack::Static` via URL Prefix Matching
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-2026-34230 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-625

V. Comments for CVE-2026-34763

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