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CVE-2026-120633— CGI versions before 5.00 for Perl trust the client X-Forwarded-Host header in url, self_url, virtual_host and virtual_port

Quick assessment

Affected
CVE-2026-120633
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.

在 Perl 5.00 之前的 CGI 版本中，系统会信任客户端请求中的 头，并将其用于 、 、 和 等参数。 当 请求头存在时，这些参数会从该头中获取主机名和端口；若该头不存在，则从 头中获取。然而，系统并未对这两个头中的内容进行任何验证。 和 所生成的 URL 会被用作默认的重定向目标、 的 属性值，以及在未设置 时 的默认 属性值。 因此，攻击者可以构造恶意请求，使共享缓存以及应用程序存储或发送的 URL 被注入重定向、链接或脚本，使其指向攻击者控制的服务器，从而实现缓存投毒（cache poisoning）

AI Predicted 6.1 Difficulty: Trivial EPSS 0.13% · P3

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 1

VendorProduct Version RangeStatus
None None < 5.00 affected

I. Basic Information for CVE-2026-120633

Vulnerability Information
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Vulnerability Title
CGI versions before 5.00 for Perl trust the client X-Forwarded-Host header in url, self_url, virtual_host and virtual_port
Source: CVE Program / CVE List V5
Vulnerability Description
CGI versions before 5.00 for Perl trust the client X-Forwarded-Host header in url, self_url, virtual_host and virtual_port. These take the host name and port from the X-Forwarded-Host request header when present, and otherwise from Host, without validating either. The URLs from url and self_url are the default redirect location and the start_html(-base=>1) base href, and the default start_form action when REQUEST_URI is not set. A client can poison shared caches, and URLs the application stores or sends, with redirects, links and scripts that point at a host it controls.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
使用不可信的源
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
- - 0 ~ 5.00 -

II. Public POCs for CVE-2026-120633

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III. Intelligence Information for CVE-2026-120633

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Other References for CVE-2026-120633 (3)

IV. Related Vulnerabilities

Same weakness: CWE-348