Pluginnaam	WP Filter & Combine RSS Feeds
Type of Vulnerability	Ontbrekende autorisatie
CVE Number	CVE-2025-7828
Urgentie	Laag
CVE Publish Date	2025-08-22
Source URL	CVE-2025-7828

WP-Firewall Security Advisory: WP Filter & Combine RSS Feeds (≤ 0.4) — Missing Authorization Allows Authenticated Contributor Feed Deletion (CVE-2025-7828)

Datum: 22 August 2025
Ernst: Low (CVSS 4.3)
CVE: CVE-2025-7828
Affected software: WP Filter & Combine RSS Feeds plugin (versions ≤ 0.4)
Required privilege for exploitation: Contributor (authenticated)
Vaste versie: N/A (no official fix at time of disclosure)

As a WordPress security team behind WP-Firewall, we monitor disclosures that affect WordPress sites and provide practical, fast guidance you can apply immediately. The recent disclosure about WP Filter & Combine RSS Feeds (≤ 0.4) discloses a broken access control issue: an authenticated user with Contributor privileges can delete RSS feeds that only higher-privileged users should be able to remove. While this is rated as low risk overall, it’s still actionable and should be addressed promptly on affected sites.

Below I’ll explain what the vulnerability means, how attackers could (and could not) use it, how to detect attempted abuse, and—most importantly—how to mitigate and protect your site. Where appropriate, I’ll include code-level guidance and recommended WAF (virtual patch) rules that are safe to deploy immediately.

---

Executive summary (short)

• Vulnerability: Missing authorization checks in the plugin allow authenticated users with the Contributor role to request feed deletion actions intended for site administrators.
• Likelihood: Low — attacker needs a Contributor account on the site.
• Impact: Low-to-moderate — deletion of configured feeds can break site features, content aggregation, and may be a stepping stone in complex attack chains.
• Immediate mitigations: Remove or deactivate the plugin; restrict contributor accounts; apply a virtual patch at the firewall (block suspicious admin requests lacking valid nonces or capability); monitor logs and backups.
• Long-term: Patch the plugin code (capability & nonce checks), apply secure coding practices, and use least-privilege principles for user roles.

---

What exactly is wrong?

The plugin exposes an action that performs feed deletion without properly verifying that the requester has a sufficient capability (for example, manage_options, manage_plugin, or another administrator-level capability) and/or without verifying a valid WordPress nonce. As a result, any authenticated account that has at least Contributor privileges can trigger the deletion routine, removing one or more configured RSS feeds from the plugin’s settings.

Key points:

• The attack requires authentication. Anonymous visitors cannot exploit this directly.
• A Contributor account is sufficient. Many sites allow contributors (guest authors, content teams, external collaborators).
• There is no official update/fix at the time of disclosure (plugin shows Fixed version: N/A). That means site owners must take protective action themselves.

---

Why the risk is scored “Low” — and why you should still act

The CVSS score (4.3) and classification as “low” reflect two facts: an attacker needs an existing account of at least Contributor privilege, and the immediate impact is limited to feed configuration (rather than full site takeover or data theft).

However:

• Feed deletion can break public-facing features (aggregated feed pages, syndicated content, cron jobs depending on feed items).
• If attackers can gain Contributor accounts via registration, compromised email/passwords, or weak admin practices, this vulnerability becomes more valuable in their toolset.
• Broken access control is a common foundation for chained attacks. Fixing these issues reduces the overall attack surface.

So even though the severity is low, we recommend prompt remediation.

---

Who is affected?

• Sites running WP Filter & Combine RSS Feeds plugin at versions ≤ 0.4.
• Sites that grant Contributor-level permissions to external people, guest authors, or any untrusted account.
• Sites that are otherwise unmonitored for changes to plugin configuration.

If you do not use this plugin — you are not directly affected. If you use the plugin but have removed Contributor accounts, or have tight user-registration controls, the risk is lower. But do not assume safety: review user accounts and plugin configuration.

---

How an attacker could misuse this (high level, non-exploitative)

An attacker with a Contributor account could:

• Visit a plugin page or call a specific endpoint (for example an admin-ajax or admin-post action or a REST route the plugin exposes) that triggers the feed deletion code path.
• Supply parameters to specify which feed to delete.
• Cause the plugin to remove one or more configured feeds from its internal settings.

Potential real-world effects:

• Aggregated pages no longer show expected content.
• Scheduled fetches or import tasks fail, which could degrade site functionality.
• In multi-site or editorial setups, content workflows may be disrupted — causing editorial or business impacts.
• If the attacker uses a Contributor account, they may already have limited content publishing ability; this action could be a distraction or part of a larger campaign.

Note: There is no public proof-of-concept included here, and I will not provide step-by-step exploit instructions. The goal is to enable defenders to protect their sites.

---

Immediate mitigations (priority order)

1. Emergency: Deactivate the plugin
   • If you can tolerate losing the plugin’s functionality temporarily, deactivate or remove the plugin until an official fix is released.
   • This completely removes the vulnerable code path.
2. Restrict Contributor accounts
   • Temporarily remove (or downgrade) guest Contributor accounts.
   • Audit user accounts: remove inactive or unknown users with elevated privileges.
3. Harden user registration & login
   • Disable open registration if enabled.
   • Enforce strong passwords and 2FA for any user with Contributor or higher roles.
4. Limit access with role management plugins
   • If you must keep the plugin active, adjust capabilities: ensure only administrators can manage plugin settings. Some role editors can map plugin-specific capabilities to administrator-only roles.
5. Virtual patch / WAF rule — deploy immediately
   • Deploy a firewall rule that blocks requests attempting to perform feed deletion unless coming from administrator-level sessions or containing a valid nonce.
   • See the “Recommended WAF rules and virtual patching” section below for safe examples designed for WP-Firewall deployment.
6. Monitor and alert
   • Turn on logging for plugin configuration changes.
   • Configure alerts for deletion of configured feeds, admin-ajax or admin-post requests from contributor accounts, and other unusual activity.
7. Back up plugin settings
   • Export plugin configuration or site backups now so you can restore a deleted feed configuration if needed.

---

Recommended detection signals (what to look for in logs)

• POST-verzoeken aan admin-ajax.php of admin-post.php with parameters that correspond to the plugin action names (look for parameters like feed_id, actie, delete_feed, delete_rss_feed, etc.). Note: action names vary by plugin; inspect plugin files to identify exact action names.
• REST API calls to /wp-json/<plugin-namespace>/ that contain DELETE or delete-like operations targeting feed resources.
• Requests that come from contributor accounts (user IDs or usernames associated with Contributor capability) and lead to changes in plugin options or database rows where feed data is stored.
• Sudden deletion of configured feeds in plugin options table (wp_opties entries) or in custom database tables the plugin uses.
• Audit logs indicating non-admin users making settings changes.

If you use WP-Firewall, enable logging level for admin requests and create alerts for admin-ajax/admin-post actions from accounts without administrator capability.

---

Safe code-level remediation (for plugin authors or site maintainers)

If you maintain the plugin or can edit its code (note: editing plugin code directly can be overwritten by updates), you should add both capability checks and nonce verification to the feed deletion handler.

Example (high-level, replace function names and parameter names with the ones actually used by the plugin):

// Example safe handler for feed deletion
function wpfcr_delete_feed_handler() {
    // Require user to be logged in
    if ( ! is_user_logged_in() ) {
        wp_send_json_error( 'Authentication required', 403 );
        exit;
    }

    // Capability check — only allow administrators / site managers
    if ( ! current_user_can( 'manage_options' ) ) {
        wp_send_json_error( 'Insufficient permission', 403 );
        exit;
    }

    // Verify nonce (replace 'wpfcr_delete_nonce' with plugin's nonce name)
    if ( ! isset( $_POST['wpfcr_nonce'] ) || ! wp_verify_nonce( $_POST['wpfcr_nonce'], 'wpfcr_delete_feed' ) ) {
        wp_send_json_error( 'Invalid request', 400 );
        exit;
    }

    // Sanitize feed ID and perform deletion safely
    $feed_id = isset( $_POST['feed_id'] ) ? intval( $_POST['feed_id'] ) : 0;
    if ( $feed_id <= 0 ) {
        wp_send_json_error( 'Invalid feed id', 400 );
        exit;
    }

    // Delete logic: use prepared calls and WordPress APIs
    // Example: remove from wp_options or custom table depending on plugin
    $deleted = wpfcr_delete_feed_by_id( $feed_id );
    if ( $deleted ) {
        wp_send_json_success( 'Feed deleted' );
    } else {
        wp_send_json_error( 'Could not delete feed', 500 );
    }
    exit;
}

If the plugin uses action hooks (admin_post_ / wp_ajax_) ensure both huidige_gebruiker_kan() En wp_verify_nonce() checks are present.

Important: Pick the right capability. Use admin-level capabilities (for example manage_options or a plugin-specific capability granted only to admins). Do not rely on contributor privileges.

---

Recommended WP-Firewall virtual patch / WAF rules

While waiting on an official plugin fix, you can deploy virtual patches at the WAF layer. Here are safe, defensive rule ideas you can use with WP-Firewall or similar WordPress security layers. These rules are intentionally conservative to avoid false positives.

Note: Replace parameter names and action values with the exact ones used by the plugin after inspecting plugin files. If you cannot identify exact actions, prefer stricter rules that check for missing nonce and check for role.

1. Block POSTs to admin endpoints that attempt feed deletion without a valid nonce
   • Behavior: Block POST requests to admin-ajax.php or admin-post.php that include feed deletion parameters and do not contain the expected plugin nonce.

   Pseudo-rule (human readable):

   • If HTTP request method == POST AND
   • (request URI contains “admin-ajax.php” OR “admin-post.php”) AND
   • request parameters contain “feed_id” (or similar) AND
   • request parameters indicate a plugin action name that performs deletion (e.g., action contains “delete” OR action equals plugin-specific action) AND
   • no valid plugin nonce parameter present OR nonce invalid
   • Then block request and log event. Return HTTP 403.
2. Require administrator session or block non-admin attempts
   • If request hits known plugin admin pages (e.g., /wp-admin/admin.php?page=wp-filter-combine-rss-feeds or similar) AND request is POST AND current session user role != administrator, block or challenge.
3. Rate-limit contributor requests to admin endpoints
   • If a user with Contributor role sends multiple admin-ajax/admin-post requests within a short time window that contain control parameters, throttle or block further actions pending manual review.
4. Block REST “delete” calls to plugin namespace originating from Contributor role or unauthenticated
   • For REST endpoints: allow DELETE only for authorized roles (mapped at WAF or application authentication check).

Example WP-Firewall rule (conceptual, not specific to any rule engine):

Rule Name: block_wpfcr_feed_delete_non_admin
Match:
  - METHOD == POST
  - (URI MATCHES "/wp-admin/admin-ajax.php" OR URI MATCHES "/wp-admin/admin-post.php")
  - REQUEST_BODY CONTAINS "feed_id" AND (REQUEST_BODY CONTAINS "delete" OR REQUEST_BODY CONTAINS "delete_feed")
  - NO REQUEST_BODY CONTAINS "wpfcr_nonce=" OR VERIFY_NONCE(request_body.wpfcr_nonce) == false
  - SESSION_USER_ROLE != "administrator"
Action: BLOCK, LOG("Blocked feed deletion attempt by non-admin without valid nonce")

Note on nonces: WAF cannot always validate a nonce (server-side verification required), but you can approximate by blocking requests that lack a nonce parameter entirely or that include obviously invalid/empty nonce fields.

If your firewall supports session/role awareness (WP-Firewall can be configured to map a logged-in user’s role), rely on role mapping: block admin actions from contributor sessions.

---

How to audit whether you’ve been impacted

1. Inspect plugin settings
   • Go to plugin settings and verify configured feeds are present. If feeds are missing or unexpectedly changed, consider it suspicious.
2. Check recent activity logs
   • Review any available audit logs for admin-ajax/admin-post access and changes to plugin options (for example, entries in wp_opties or custom tables).
   • Look for entries where a Contributor user initiated requests at times they shouldn’t have.
3. Database checks
   • If the plugin stores feeds in wp_opties (or a known option name), check historical backups and compare the serialized option entries to detect deletions.
4. Backup comparison
   • Compare site backups taken before and after the disclosure date to detect removed feeds.
5. WordPress logs and server logs
   • Check webserver access logs for POST requests to admin endpoints that align with feed deletion times.

If you find suspicious activity, proceed with the incident response checklist below.

---

Incident response checklist

• Immediately export current configuration and site backup.
• Re-enable the plugin only after virtual patching or code fixes are applied; otherwise deactivate.
• Rotate passwords and force logout for all non-admin users if you suspect account compromise.
• Restore missing feeds from backups or manual reconfiguration.
• Identify how the Contributor account was created or compromised; remove the account if untrusted.
• Keep forensic copies of logs and backups for analysis.
• Notify stakeholders (editors, site owners) about disruption and remediation steps.
• Implement long-term fixes: patched plugin, capability checks, wp_verify_nonce usage, and improved role governance.

---

Secure development recommendations for plugin authors

If you are a plugin author, the recurring issues we see with broken access control can be avoided by integrating these practices into your development lifecycle:

• Fail closed: Deny actions by default and explicitly allow them to known-capability holders.
• Use capability checks: Use huidige_gebruiker_kan() with admin-level capabilities (or plugin-specific capabilities that are only assigned to admin-level roles).
• Verify nonces: Add wp_nonce_veld() on admin forms and wp_verify_nonce() in handlers.
• Avoid assumptions about roles: Don’t assume a contributor cannot abuse an endpoint — always check capabilities.
• Sanitize and validate inputs: Use intval, sanitize_text_field, esc_attr, etc., and validate types.
• Use REST/ AJAX endpoints safely: For REST, use permission_callback that enforces capability checks. For AJAX, ensure wp_ajax_ actions check permissions.
• Logging & audit: Log sensitive actions with user ID, timestamp, IP address and parameter set.
• Unit tests & security review: Include unit tests for capability checks and implement security review as part of release process.

---

Example hardening for REST endpoints

If the plugin exposes a REST route for feed deletion, ensure the route registration includes a permission callback:

register_rest_route(
    'wpfcr/v1',
    '/feeds/(?P<id>\d+)',
    array(
        'methods'  => 'DELETE',
        'callback' => 'wpfcr_rest_delete_feed',
        'permission_callback' => function() {
            return current_user_can( 'manage_options' );
        },
    )
);

This ensures DELETE requests are allowed only for users with manage_options capability.

---

Why virtual patching at the WAF is a good temporary measure

• Fast: WAF rules can be deployed immediately to block hazardous requests while you wait for a plugin fix.
• Non-destructive: Properly scoped rules avoid breaking legitimate traffic when implemented conservatively.
• Defense-in-depth: Adds another layer so even if code lacks checks, the request does not reach it.
• Monitoring: WAF logs give you visibility into attempted exploitation.

WP-Firewall supports targeted virtual patches to block admin endpoint abuse, throttle suspicious accounts, and alert you to suspicious activity, so you can stay protected even with unpatched plugins.

---

Practical checklist for site owners (step-by-step)

1. Identify — check if the plugin is installed and version ≤ 0.4.
2. Backup — create a full site backup (files + database).
3. Deactivate plugin — if feasible, to remove the vulnerable code path.
4. Audit users — remove unknown contributors; enforce password reset for current contributors.
5. Deploy WAF rule — block feed deletion actions from non-admins / block missing nonce flows.
6. Monitor logs — focus on admin-ajax/admin-post REST calls and option changes.
7. Restore feeds — if feeds were deleted, restore from backup or reconfigure.
8. Plan update — when plugin author releases a patch, test and update.
9. Post-mortem — document what happened, how it was fixed, and process improvements.

---

Frequently asked questions (FAQ)

Q: Can an anonymous attacker exploit this?
A: No. The vulnerability requires an authenticated account with at least Contributor privileges.

Q: Is site takeover possible using this bug alone?
A: Not directly. The immediate impact is configuration changes (feed deletion). However, misconfigurations and broken access control may be chained with other vulnerabilities or misused by attackers who already control low-privileged accounts.

Q: How quickly should I act?
A: Immediately. If you use the plugin, either deactivate it or apply virtual patches and audit accounts right away.

Q: What if I depend on this plugin for core site functionality?
A: Create a plan to temporarily restrict who can manage plugin settings (administrators only), deploy WAF rules, and request or implement a safe code fix. Consider replacing the plugin with a maintained alternative if no fix is available.

---

Example WAF rule snippets (conceptual)

Below are conceptual WAF policies designed to be adapted to your platform. They are conservative — please test in staging before wide deployment.

1. Block POST to admin-ajax with feed deletion indicators and no nonce:

• Condition:
  • REQUEST_METHOD == POST
  • REQUEST_URI contains “admin-ajax.php”
  • REQUEST_BODY contains “feed_id” AND (REQUEST_BODY contains “delete” OR REQUEST_BODY contains “delete_feed”)
  • REQUEST_BODY does NOT contain “wpfcr_nonce” OR REQUEST_BODY.wpfcr_nonce == “”
• Action: Block + Log

2. Restrict admin-menu POSTs to admin users:

• Condition:
  • REQUEST_URI contains “/wp-admin/”
  • REQUEST_METHOD == POST
  • SESSION_USER_ROLE != “administrator”
  • REQUEST_REFERER contains “wp-filter-combine-rss-feeds” (or plugin admin page)
• Action: Block / Challenge

3. Rate-limit contributor requests to admin actions:

• Condition:
  • SESSION_USER_ROLE == “contributor”
  • REQUEST_RATE > 5 requests per minute to admin-ajax/admin-post
• Action: Throttle / Challenge

Work with your security operations team to match actual plugin parameter names and admin page slugs.

---

Long-term remediation & process improvements

• Keep plugin inventory: know which plugins are installed and their versions.
• Subscribe to vulnerability feeds for plugins you rely on.
• Establish an incident playbook for plugin-based problems (backup, virtual patching, user audit, vendor follow-up).
• Reduce exposure by assigning only necessary roles — limit Contributor-level access if not required.
• Enforce stronger identity controls for editorials: 2FA, account verification, and periodic access reviews.

---

Closing thoughts

Broken access control issues like this are reminders that principle of least privilege and explicit authorization checks are essential in WordPress plugins. Even seemingly small administrative features (feed management) should enforce server-side capability checks and nonce verification. For site operators, the combination of quick detection, temporary virtual patching, and prudent account management reduces risk while waiting for vendor fixes.

As defenders, our priority is to keep your site operating securely and resiliently. If you need assistance implementing the WAF rules described above, or want help auditing user roles and lockdowns, WP-Firewall can help with rapid deployment and targeted protection so you can keep running while the plugin author prepares a fix.

---

Protect Your Site Today — Start with WP-Firewall Free Plan

If you want hands-on protection right away, consider our free WP-Firewall Basic plan. It includes a managed firewall, WAF rules, unlimited bandwidth protection, a malware scanner, and mitigation for OWASP Top 10 risks. That lets you deploy virtual patches and monitoring quickly without additional cost. Sign up for the free plan here: https://my.wp-firewall.com/buy/wp-firewall-free-plan/

Why choose Basic (Free)?

• Essential protection with managed firewall and WAF
• Unlimited bandwidth so your protection scales with your site
• Malware scanner and detection for common attack patterns
• Mitigation rules that cover OWASP Top 10 issues, helping you stop exploitation attempts before they reach the vulnerable plugin code

If you need more automated remediation and vulnerability patching, our paid plans include automatic malware removal, blacklist/whitelist controls, virtual patching, monthly security reports, and dedicated assistance to harden your site.

---

If you prefer hands-on assistance, WP-Firewall support can help deploy the virtual patching rules, audit user privileges, and restore any lost configuration. Reach out via your WP-Firewall console and let us help you secure the site quickly and safely.