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CVE-2026-104021— Fastcache by Host.it <= 1.7.4 - Authenticated (Administrator+) Code Injection via .htaccess Directive Injection via 'cache_cookie_exclude' Setting

Quick assessment

Affected
hostspa Fastcache by Host.it
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.

Host.it 开发的 WordPress 插件 Fastcache 在 1.7.4 及更早版本中存在代码注入漏洞，该漏洞可通过 参数利用。问题根源在于：该插件通过 函数注册 设置时，未提供 （清理回调函数）；而在 函数中，仅对每个 cookie 值应用 函数进行简单清洗，随后便将其直接插入 Apache 的 指令行中。 仅去除值两端的空白字符，却无法清除嵌入的换行符，从而使攻击者能够突破捕获组的边界，追加任意指令。 此漏洞允许拥有管理员权限及以上级别的认证攻击者，利用 函数将任意的 Apache 配置指令注入网站

CVSS 7.2 · High
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I. Basic Information for CVE-2026-104021

Vulnerability Information
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Vulnerability Title
Fastcache by Host.it <= 1.7.4 - Authenticated (Administrator+) Code Injection via .htaccess Directive Injection via 'cache_cookie_exclude' Setting
Source: CVE Program / CVE List V5
Vulnerability Description
The Fastcache by Host.it plugin for WordPress is vulnerable to Code Injection in all versions up to, and including, 1.7.4 via the `fastcache_settings[cache_cookie_exclude][]` parameter. This is due to the plugin registering the `cache_cookie_exclude` setting via `register_setting()` without a `sanitize_callback`, while `buildSiteHtaccessRules()` applies only `trim()` to each cookie value before interpolating it directly into an Apache `RewriteCond` line — a normalization that strips surrounding whitespace but leaves embedded newlines intact, allowing an attacker to break out of the capture group and append arbitrary directives. This makes it possible for authenticated attackers, with administrator-level access and above, to inject arbitrary Apache directives into the site's `.htaccess` file via `file_put_contents()`, enabling server-level configuration changes such as setting `php_value auto_prepend_file` to execute attacker-controlled PHP code on every request.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
对生成代码的控制不恰当(代码注入)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
hostspa Fastcache by Host.it 0 ~ 1.7.4 -

II. Public POCs for CVE-2026-104021

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III. Intelligence Information for CVE-2026-104021

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Other References for CVE-2026-104021 (7)

IV. Related Vulnerabilities

Same weakness: CWE-94

V. Comments for CVE-2026-104021

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