CVE-2026-10821— Yoast SEO Premium < 27.6.1 - Author+ Arbitrary .htaccess Directive Injection to RCE
Quick assessment
Affected
Unknown Yoast SEO Premium
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 27.6.1 版本之前，Yoast SEO Premium WordPress 插件在启用基于文件的重定向模式时，未对重定向来源中的控制字符进行净化，就直接将其写入站点的 Apache 配置文件中，且创建重定向的端点对仅具有作者（Author）权限的用户也是可访问的。这允许此类用户向根目录下的 .htaccess 文件中注入任意以换行符分隔的 Apache 指令。在支持 PHP 指令的 Apache 服务器上，该注入可与用户自身上传的媒体文件（即携带 PHP 负载的多语言图像文件）以及 auto_prepend
Possible ATT&CK Techniques 1 AI
T1190 · Exploit Public-Facing Application
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I. Basic Information for CVE-2026-10821
Vulnerability Information
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Vulnerability Title
Yoast SEO Premium < 27.6.1 - Author+ Arbitrary .htaccess Directive Injection to RCE
Source: CVE Program / CVE List V5
Vulnerability Description
The Yoast SEO Premium WordPress plugin before 27.6.1 does not sanitize control characters from redirect origins before writing them to the site's Apache configuration file when the file-based redirect mode is enabled, and the redirect-creation endpoint is reachable by users with only Author-level access. This allows such users to inject arbitrary newline-delimited Apache directives into the root .htaccess file. On Apache servers that honour PHP directives, the injection can be chained with the user's own media upload (a polyglot image carrying a PHP payload) and an auto_prepend_file directive to achieve Remote Code Execution.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Affected Products
| Vendor | Product | Affected Versions | CPE | Subscribe |
|---|---|---|---|---|
| Unknown | Yoast SEO Premium | 0 ~ 27.6.1 | - |
|
II. Public POCs for CVE-2026-10821
| # | POC Description | Source Link | Shenlong Link |
|---|
AI-Generated POC
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Other References for CVE-2026-10821 (2)
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🔗 Yoast SEO Premium < 27.6.1 – Author+ Arbitrary .htaccess Directive Injection to RCE | CVE 2026-10821 | Plugin Vulnerabilities Read full article exploit vdb-entry technical-description
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Same Patch Batch · Unknown · 2026-09-02 · 66 CVEs total
| CVE-2026-4357 | 10.0 CRITICAL | Embed HTML5 Game <= 1.3 - Unauthenticated Arbitrary File Upload |
| CVE-2026-77009 | 9.9 CRITICAL | WatchMan-Site7 3.1.1 - 4.2.0 - Subscriber+ RCE via Debug Console |
| CVE-2025-9314 | 9.8 CRITICAL | Developer Tools <= 1.1.3 – Unauthenticated Arbitrary File Upload |
| CVE-2025-15485 | 8.2 HIGH | Auto x LINE <= 1.0.0 – Unauthenticated REST API Endpoints Call |
| CVE-2026-83547 | 6.8 MEDIUM | Xpro Elementor Addons 1.6.0 - 1.7.3 - Contributor+ Stored XSS via Multiple Widgets |
| CVE-2026-82884 | 6.8 MEDIUM | All in One SEO < 5.0.0.1 - Contributor+ Stored XSS via ai-assistant Block |
| CVE-2026-2688 | 6.5 MEDIUM | CM HIPAA Forms < 3.2.0 - Unauthenticated Authorization Bypass |
| CVE-2024-3773 | 5.9 MEDIUM | LiveJournal Shortcode <= 1.1.1 - Contributor+ Stored XSS via Shortcode |
| CVE-2026-2811 | 5.4 MEDIUM | Ajaxify Comments < 3.2 - Unauthenticated HTTP Header Injection |
| CVE-2026-8151 | 5.4 MEDIUM | Simple Membership MailChimp Integration < 1.9.8 - API Key Update via CSRF |
| CVE-2026-78153 | 5.3 MEDIUM | Restrict User Access 2.6 - 2.8 - Unauthenticated Content Protection Bypass via REST API Ro |
| CVE-2025-15489 | 5.3 MEDIUM | Passster < 4.2.24 - Password Protection Bypass |
| CVE-2025-15481 | 5.3 MEDIUM | Notification Bar for WordPress <= 1.1.8 – Unauthenticated Subscriber Data Disclosure |
| CVE-2025-15490 | 5.3 MEDIUM | Passster < 4.2.26 - Global Protection Bypass |
| CVE-2025-8945 | 5.3 MEDIUM | Wp Edit Password Protected < 1.3.5 - Protection Bypass via REST API |
| CVE-2026-83533 | 5.3 MEDIUM | WP Express Checkout < 2.4.9 - Unauthenticated Payment Bypass via wpec_process_payment |
| CVE-2026-77794 | 5.3 MEDIUM | RegistrationMagic 6.0.0.0 - 6.0.9.8 - Unauthenticated Payment Bypass via Zero Quantity |
| CVE-2026-17563 | 5.3 MEDIUM | WP User Frontend < 4.3.11 - Unauthenticated Post Creation via Subscription-Gated Form |
| CVE-2026-77793 | 5.3 MEDIUM | RegistrationMagic < 6.0.9.9 - Unauthenticated Payment Bypass via Omitted Price Field |
| CVE-2026-81571 | 4.8 MEDIUM | Brave Popup Builder < 0.8.8 - Unauthenticated Arbitrary Shortcode Execution via UTM Parame |
Showing top 20 of 66 CVEs. View all on vendor page → →
IV. Related Vulnerabilities
Same vendor: Unknown
-
CVE-2026-2811
Ajaxify Comments < 3.2 - Unauthenticated HTTP Header Injecti -
CVE-2025-9314
Developer Tools <= 1.1.3 – Unauthenticated Arbitrary File Up -
CVE-2025-8945
Wp Edit Password Protected < 1.3.5 - Protection Bypass via R -
CVE-2025-15490
Passster < 4.2.26 - Global Protection Bypass -
CVE-2025-15489
Passster < 4.2.24 - Password Protection Bypass
V. Comments for CVE-2026-10821
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