Tên plugin	eDS Responsive Menu
Type of Vulnerability	Tiêm đối tượng PHP
CVE Number	CVE-2025-58839
Tính cấp bách	Thấp
CVE Publish Date	2025-09-05
Source URL	CVE-2025-58839

CVE-2025-58839 — PHP Object Injection in eDS Responsive Menu (≤ 1.2): What WordPress Site Owners Must Do Now

Tác giả: Nhóm bảo mật WP-Firewall
Date: 2025-09-05

A recently disclosed vulnerability (CVE-2025-58839) affects the WordPress plugin “eDS Responsive Menu” in versions up to and including 1.2. The issue is a PHP Object Injection (POI) vulnerability that can be leveraged to perform a wide variety of attacks — from code execution to privilege escalation — if a suitable gadget/POP chain exists. The plugin appears to be abandoned (no official fix available at time of writing), and the vulnerability requires an Administrator privilege on the site to exploit. That administrative requirement reduces remote, unauthenticated risk — but does not remove it. In this advisory we explain the vulnerability in plain language, outline how it could be abused, and give practical, prioritized steps for WordPress site owners, administrators and plugin developers to protect their sites immediately and long term.

This advisory is written from the perspective of WP-Firewall (a WordPress firewall and security service). We’ll cover detection, mitigation, and how our tools can help protect you quickly even when there is no official patch available.

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Executive summary — what you need to know right now

• Điểm yếu: PHP Object Injection (POI) in eDS Responsive Menu plugin versions ≤ 1.2 (CVE-2025-58839).
• Exploitation prerequisites: attacker must have Administrator privileges on a vulnerable site to trigger the vulnerability.
• Mức độ nghiêm trọng: The vulnerability itself is an injection flaw with serious theoretical impact (remote code execution, SQL injection, path traversal, denial of service) when paired with a proper POP/gadget chain. Because it requires admin privileges to exploit, it is currently treated with lower patch priority — but abuse remains possible and dangerous.
• Official fix: None published at time of disclosure. The plugin appears unmaintained/abandoned.
• Immediate action recommended: Remove or replace the plugin, lock down admin accounts, rotate credentials, run thorough scans for signs of compromise, and deploy virtual patching (WAF rules) where available.

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What is PHP Object Injection (POI) — a plain-English explanation

PHP Object Injection occurs when an application unserializes user-controlled data without proper validation or restrictions. The PHP function unserialize() converts a serialized string back into PHP values and objects. If an attacker can control the serialized input, they can craft payloads that instantiate objects of classes that exist in the application codebase. If those classes contain magic methods (for example __wakeup(), __destruct(), __toString()) or other logic that performs filesystem, database, or execution tasks, the attacker may trigger dangerous behavior — this is often referred to as a POP (Property-Oriented Programming) or gadget chain.

Key concepts:

• Serialized data: Strings that represent complex PHP variables (arrays, objects) used for storage, caching, session data, or inter-process transmission.
• Untrusted input: Any data that could be influenced by a user (POST data, cookie values, option fields).
• Gadget chain / POP chain: A sequence of objects / methods present in the application that when deserialized and invoked in sequence result in the attacker’s desired effect (for example writing files, executing commands, or making SQL calls).

Because many WordPress plugins and themes include object-oriented code, an insecure unserialize() call in any one place can be dangerous site-wide if a suitable gadget chain exists.

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Why CVE-2025-58839 matters (even though it needs admin privileges)

At first glance, a vulnerability that requires Administrator privileges might seem less urgent. However, consider the following:

• Administrator accounts are commonly the target of credential theft (phishing, reused passwords, credential stuffing). Once an attacker gets admin access, they can chain this vulnerability into more severe outcomes.
• A previously compromised admin or a malicious insider could exploit this to persist on the site, plant backdoors, or pivot to the server.
• Even if a remote, unauthenticated exploit is infeasible today, the availability of a POI vulnerability makes the site much more attractive to an attacker who has any foothold.
• The plugin is reportedly abandoned. Without official fixes, the window of exposure remains open indefinitely unless you take action.

In short: the administrative requirement reduces the probability of casual automated compromise but does not eliminate the real-world risk for many sites.

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The specifics: eDS Responsive Menu (≤ 1.2)

• Affected software: eDS Responsive Menu (WordPress plugin)
• Các phiên bản dễ bị tấn công: ≤ 1.2
• Vulnerability type: PHP Object Injection (OWASP classification: A3 — Injection)
• CVE: CVE-2025-58839
• Exploitation privileges: Administrator
• Phiên bản cố định: None available (as of writing)
• Researcher credit: reported responsibly by an independent researcher

Patch availability: None. The plugin appears to have not been updated for more than a year, which often indicates abandonment. That leaves site owners responsible for mitigation and replacement choices.

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High-level description of how an attacker could exploit this (safe overview)

We will not provide step-by-step exploit code. Instead, here’s a conceptual view:

1. The plugin exposes an endpoint or processes data that is passed to PHP unserialize() without safely restricting allowed object classes or validating the input.
2. An attacker with Administrator privileges can supply crafted serialized data — for example by editing plugin options, importing settings, or uploading crafted POST data that reaches the vulnerable unserialize call.
3. When PHP unserializes the payload, objects of existing classes in the WordPress codebase (core, themes, plugins) are instantiated with attacker-controlled properties.
4. If the codebase contains a sequence of classes and methods whose execution triggers a side-effect (file write, eval, shell execution, database operations), the attacker can leverage that chain to perform actions beyond the initial privilege level.
5. Consequences range widely depending on the gadget chain, from modification of content to remote code execution and full site takeover.

Because the specifics depend on the classes present on the server, the exact payloads are site-specific. That makes detection harder and mitigation more important.

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Indicators of compromise (IoCs) and detection guidance

If your site uses eDS Responsive Menu (≤ 1.2), watch for the following suspicious signs. These are high-level indicators; absence of these signs doesn’t guarantee safety.

• Unexpected changes in the WordPress options table (wp_tùy_chọn) — look for fields updated by an admin account you don’t recognize or with serialized content that looks obfuscated.
• New admin users, changes to user roles or permissions, or modified admin emails.
• Unexpected files in plugin/theme directories or new files in wp-content/tải lên that contain PHP code.
• Unexpected scheduled tasks (cron jobs) that you didn’t create.
• Unusual outbound network activity from the site (HTTP requests to unusual domains).
• Unusual presence of suspicious code in theme files, especially files modified around the time of suspected compromise.
• Modified .htaccess rules, unfamiliar server-side cron jobs, or PHP files added to upload directories.
• Elevated error logs referencing unserialize() or unexpected class names being autoloaded.

How to scan:

• Use a file integrity scanner to compare current files with clean copies of WordPress core and themes.
• Search your database (wp_tùy_chọn, wp_usermeta, wp_posts) for serialized strings containing class names or suspicious content. Serialized objects start with O:<length>:"ClassName".
• Review recent admin activity in WP (if you have logging enabled).
• Run a malware scan with a trusted scanner and consider a second opinion from a host-based scanner.

Important: many scanners have false positives. If you suspect compromise, isolate the site (maintenance mode), take a full backup, and proceed with a careful investigation.

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Immediate actions for site owners (ordered by priority)

1. Identify whether your site is using the vulnerable plugin and the version:
   • Dashboard → Plugins → Installed Plugins. If present and version ≤ 1.2, you are exposed.
2. If you cannot immediately remove the plugin, lock down Administrator access:
   • Temporarily disable accounts you do not recognize.
   • Force a password reset for all admin users; require strong passwords and unique credentials.
   • Disable remote admin access and two-factor authentication should be enabled for all admins as soon as possible.
3. If practical, remove the plugin entirely:
   • Deactivate and delete eDS Responsive Menu from the plugin list. Deleting removes plugin files but may leave data in the DB.
4. If you cannot delete immediately, restrict access to plugin endpoints via server rules:
   • Add a server-level deny rule for known plugin files or endpoints, or restrict access by IP to admin pages using web server config or hosting firewall.
   • If you run a WAF (web application firewall), enable a virtual patch rule to block suspicious serialized payloads and POST requests to vulnerable plugin endpoints.
5. Rotate credentials:
   • Change all admin passwords, database user credentials used by WordPress, and any API tokens (including hosting control panel and FTP).
6. Backup:
   • Take a full offline backup of files and the database before proceeding with removals or investigations.
7. Scan:
   • Run a full malware scan (file and DB) to detect indicators of compromise.
   • If you find suspicious injections, unauthorized files, or persistent backdoors, consider engaging professional incident response.
8. Monitor logs:
   • Keep close watch of access logs and WP activity logs for anomalous admin actions or imports.
9. Consider temporary site isolation:
   • If the evidence suggests compromise, move the site to a staging environment for investigation and restore a clean copy.

If you’re a WP-Firewall customer, use our dashboard to enable virtual patching and scanning immediately (see the WP-Firewall section below for details).

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Developer guidance: how to fix this properly (for plugin/theme authors)

If you maintain a plugin or theme that uses unserialize() on data that could be influenced by users, please apply the following best practices:

1. Avoid unserialize() on untrusted input:
   • Prefer JSON (json_encode/json_decode) for serializing data. It does not instantiate PHP objects.
2. If you must use unserialize(), use the allowed_classes option (PHP 7.0+):
   • unserialize($data, ['allowed_classes' => false]) — this prevents object instantiation.
   • Or, specify a safe list of classes if object deserialization is required.
3. Validate and sanitize inputs:
   • Never assume data from POST, GET, cookies, or option fields is trusted. Apply explicit validation and sanitation.
4. Implement capability checks and nonces:
   • Ensure operations that modify plugin options or settings require appropriate capability checks (current_user_can('manage_options')) and nonces (wp_verify_nonce).
5. Keep code minimal and avoid side effects in magic methods:
   • Avoid performing destructive operations (file writes, external calls) within __wakeup(), __destruct(), or other magic methods.
6. Use prepared statements for database interactions:
   • Sử dụng $wpdb->prepare() and parameterized queries to prevent SQL injection.
7. Implement logging and alerting for admin-level changes:
   • Log significant changes to options or settings, and consider emailing site owners when critical settings change.

If you are the plugin author: publish a fixed version that removes unsafe unserialize usage, document the change, and publish migration instructions for administrators.

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Why a virtual patch (WAF) is critical when no official fix is available

When a vendor hasn’t released a patch, WAF-based virtual patching is often the fastest way to reduce risk. A virtual patch differs from a code patch: it prevents exploitation at the HTTP/application layer without modifying the vulnerable code.

Typical protections a WAF can provide for POI vulnerabilities:

• Block HTTP requests that contain suspicious serialized object payloads (serialized PHP object patterns).
• Block or monitor POST/PUT requests to plugin-specific endpoints that are not normally used by administrators.
• Throttle and block repeated attempts to modify plugin options or upload crafted payloads.
• Apply rule that requires authenticated admin actions to originate from verified sessions/IP ranges.
• Alert onsite administrators to attempted exploitation attempts in real time.

Remember: virtual patching reduces risk but does not fix the underlying insecure code. Removing or replacing the unmaintained plugin is the long-term solution.

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How WP-Firewall helps — immediate protections we provide

(Short overview of service features and practical steps WP-Firewall customers can use to reduce risk right now.)

1. Automatic WAF rules and virtual patching:
   • WP-Firewall deploys rules to detect and block serialized PHP object payloads and known exploitation patterns. When the eDS Responsive Menu POI was disclosed, our engineers created and deployed a virtual patch (WAF rule) to block requests that match the exploitation vectors we observe in the wild.
2. Managed firewall and unlimited bandwidth:
   • Our managed firewall provides always-on protection for site admin areas and plugin endpoints.
3. Malware scanning and mitigation:
   • Our scanner looks for unexpected PHP files, suspicious code modifications and injected backdoors. For paid plans, automated removal tools help clean obvious infections.
4. Admin account hardening and monitoring:
   • Activity logs and alerts help you detect unexpected admin changes quickly.
5. Incident response and support:
   • For sites on higher-tier plans, our team assists with incident triage and cleanup.

How to act right now if you have WP-Firewall:

• Log in to your WP-Firewall dashboard and ensure virtual patching / WAF rules are enabled.
• Enable strict blocking for serialized object patterns and restrict POSTs to plugin paths if you don’t need remote configuration capabilities.
• Run an on-demand malware scan and review any findings.
• Enable admin account monitoring and set up email/SMS alerts for suspicious activity.

Note: If you are not yet protected by WP-Firewall, we offer a free plan with essential protections to help mitigate vulnerabilities like this one while you evaluate further steps.

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Detailed remediation checklist (step-by-step)

This checklist is designed to be followed by WordPress administrators and security teams. Treat every step as important and adapt to your environment.

1. Inventory & verification
   • Confirm whether eDS Responsive Menu is installed and its version number.
   • Identify all administrator accounts and service accounts on the site.
2. Short-term containment
   • If the site is actively used in production, set it to maintenance mode during remediation when feasible.
   • Deactivate and delete the eDS Responsive Menu plugin.
   • If unable to delete, restrict access to wp-admin URLs to known IPs via server-level controls temporarily.
3. Credentials & access
   • Force password reset for all admin users and any user with elevated privileges.
   • Enable two-factor authentication for all admin accounts.
   • Rotate database credentials and API keys used by plugins as appropriate.
4. Hỗ trợ
   • Take a full site backup (files and DB) and store it offline before making significant changes.
5. Clean-up & validation
   • Scan for malware and remove identified backdoors (pro-grade tools or professional assistance recommended).
   • Remove files that are not part of the theme/plugin/core or that contain injected PHP.
   • Inspect wp_tùy_chọn Và wp_usermeta for suspicious serialized values; revert to known-good values from backups if needed.
6. Monitoring & hardening
   • Enable WP-Firewall WAF rules, hardening settings, and regular scans.
   • Implement activity logging for all admin actions.
   • Schedule regular security audits.
7. Long-term replacement
   • Replace an abandoned plugin with a maintained, actively supported alternative. Confirm the substitute does not use unsafe unserialize() calls.
   • If you have custom code that relies on unserialize(), fix it following developer guidance above.
8. Incident response (if compromise is confirmed)
   • Engage incident response professionals if you find signs of compromise you cannot safely clean.
   • Consider a full site rebuild from a known clean codebase if persistence mechanisms are deeply embedded.

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Incident response: if you believe you’ve been exploited

If you find indicators that the site has already been compromised:

• Isolate the site from the network if possible (bring site offline).
• Preserve logs and take forensic backups.
• Engage a professional incident response team experienced with WordPress compromises.
• Consider restoring from a backup taken prior to suspected compromise — but be aware that restoring an infected backup will reintroduce vulnerabilities unless the root cause is removed.
• Notify stakeholders (hosting provider, clients) as required by your policies.

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Why plugin abandonment matters and how to reduce dependency risk

Plugins are a critical part of WordPress’ extensibility, but they’re also a major attack surface. An abandoned plugin is a liability because:

• No security patches are released when new issues are found.
• Compatibility problems with newer PHP/WordPress versions may surface.
• Dependency chains across plugins and themes may introduce additional gadgets that can be abused with POI vulnerabilities.

How to reduce risk:

• Prefer plugins that have a history of timely updates, active support, and a public changelog.
• Regularly review your plugin list and remove plugins you don’t actively use.
• Use staging environments to test plugin updates before applying to production.
• Maintain a rollback plan and regular backups.

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Closing notes — security is continuous

CVE-2025-58839 is an important reminder that vulnerabilities are not just theoretical; they become operational threats when code handling untrusted data is present. The administrative privilege requirement lowers remote, unauthenticated risk but does not eliminate the danger — particularly when credentials are weak or reused.

Your options are straightforward:

• Remove or replace unmaintained plugins now.
• Lock down administrative access and rotate credentials.
• Deploy virtual patches via a capable WAF immediately to reduce the risk window while you plan replacements.
• Perform a full audit and adopt stronger operational security practices: logging, monitoring, MFA, limited admin users, and frequent backups.

If you would like help implementing virtual patches, running deep malware scans, or rebuilding safely, WP-Firewall is ready to assist. Our free plan provides immediate, essential protections to help block exploitation patterns while you remediate.

Stay safe, keep your admin accounts locked down, and treat abandoned plugins as priority removal candidates.

— WP-Firewall Security Team

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References and further reading

• PHP manual: unserialize() options and allowed_classes (search “unserialize allowed_classes”)
• OWASP: Injection categories and defensive guidance
• WordPress hardening guides: admin credential best practices and capabilities

(If you need step-by-step help from our security team, log into your WP-Firewall dashboard or visit https://my.wp-firewall.com/buy/wp-firewall-free-plan/ to get started with our free plan.)