Plugin Name	Upsell Order Bump Offer for WooCommerce
Type of Vulnerability	Broken Authentication
CVE Number	CVE-2026-49110
Urgency	High
CVE Publish Date	2026-06-06
Source URL	CVE-2026-49110

Urgent: Price Manipulation / Broken Authentication in ‘Upsell Order Bump Offer for WooCommerce’ (≤ 3.1.4) — What Store Owners Must Do Now

Author: WP­Firewall Security Team

Summary: A broken authentication vulnerability affecting Upsell Order Bump Offer for WooCommerce (versions ≤ 3.1.4) has been assigned CVE­2026­49110 and a CVSS base score of 7.5. The issue allows an unauthenticated actor to manipulate price-related parameters under certain conditions. A patch is available in version 3.1.5. If you run WooCommerce and this plugin, read this advisory carefully — it covers technical details, exploitation scenarios, detection, step­by­step mitigation, incident response, developer fixes, and how WP­Firewall can protect your store while you patch.

TL;DR (quick action checklist)

• Vulnerable plugin: Upsell Order Bump Offer for WooCommerce, versions ≤ 3.1.4.
• CVE: CVE­2026­49110
• Risk class: Broken Authentication → OWASP A7. CVSS 7.5.
• Patched in: 3.1.5 — update immediately.
• If you cannot update right away:
  • Deactivate the plugin.
  • Put the site into maintenance mode for checkout processes OR implement WAF rules to block exploit attempts.
  • Monitor for suspicious orders or modified order metadata.
  • Rotate admin credentials and WooCommerce API keys if you detect suspicious activity.
• WP­Firewall recommendation: enable managed WAF + malware scans, apply virtual patching if available, enable automatic plugin updates for this plugin where possible.

Background — what was disclosed

A vulnerability affecting the Upsell Order Bump Offer for WooCommerce plugin (versions up to and including 3.1.4) has been published and assigned CVE­2026­49110. The issue is classified as “Broken Authentication” and the key takeaway is that an unauthenticated actor can manipulate price-related fields under certain circumstances. The vendor released a patch in version 3.1.5 to correct authentication/authorization checks.

Broken authentication vulnerabilities often arise when code that modifies orders, prices, or upsell/bump configuration fails to verify that the requestor is an authorized user (for example, an administrator or a properly authenticated shop manager), or when actions that should require valid nonces/permissions can be invoked by unauthenticated clients (e.g., via a REST/HTTP endpoint or AJAX action).

The disclosed properties for this advisory include:

• Required privilege: Unauthenticated (exploit does not require an authenticated WordPress user in some scenarios).
• Attack surface: Web requests targeting the plugin’s endpoints/hooks that handle order-bump/upsell price handling.
• Impact: Price manipulation on orders (customers or attackers could alter price fields or apply unauthorized discounts), leading to financial loss or exploitation of purchase workflows. In chained exploits, this could contribute to privilege escalation or persistent compromise.
• Mitigation: Upgrade to version 3.1.5 or later.

Why this matters for WooCommerce stores

Upsell and order bump plugins interact directly with pricing and checkout flows. That means a vulnerability that allows unauthenticated manipulation of price or discount fields can directly translate into:

• Lost revenue — attackers may be able to alter prices to extremely low values or zero.
• Fraudulent orders — artificially discounted purchases can be used to launder payments or test stolen cards.
• Accounting and reconciliation headaches — order metadata changed outside expected flows.
• Customer trust damage — if orders are mishandled, customers or payment processors may raise disputes.
• Further security escalation — attackers who can influence order logic may attempt to inject malicious payloads, escalate privileges, or create backdoor orders that trigger other actions.

Even when the vulnerability alone is “low” or “medium” severity, the real-world impact on an online store (financial and reputational) can be severe.

Exploitation scenarios (realistic examples)

We cannot reproduce the exploit code here, but below are plausible exploitation scenarios based on the “broken authentication / price manipulation” description. These are the types of behaviors you should consider when hunting for signs of exploitation.

1. Unauthenticated REST/AJAX call modifies bump price:
   • The plugin exposes a REST route or AJAX action to set or calculate order bump price. The endpoint does not verify authentication/nonce or capability properly, allowing anyone to submit a request to set a custom price for a bump item at checkout.
2. Tampered checkout request overwrites price:
   • The checkout code uses untrusted POST or JSON parameters to set the final price without validating or re-calculating server-side. An attacker can submit crafted checkout requests to set line item price to a lower amount.
3. Price override via order meta injection:
   • A public endpoint allows creation or update of order meta keys related to the bump/upsell. If that data is later used in price calculations without validation, the attacker can alter order totals.
4. Exploit chain leading to admin-level actions:
   • Price manipulation can be paired with logic flaws that trigger notifications, internal workflows, or add coupons with elevated privileges. Combined with weak admin credentials or other plugin flaws, attackers may escalate access.

Given the unauthenticated nature, mass exploitation is feasible — automated scans and scripts can probe many sites quickly.

Indicators of Compromise (IoCs) and what to look for

If you run this plugin, check the following immediately:

• Plugin version ≤ 3.1.4 installed.
• Unexpected or unusual orders:
  • Orders with zero or abnormally low totals.
  • Orders where line item prices differ from product base price, and the difference isn’t explained by coupons or legitimate discounts.
• Order meta with unexpected keys or values referencing “bump”, “upsell”, “offer”, “price_override”, or similar fields.
• Unusual access logs:
  • POST/GET requests to plugin-specific endpoints (identify endpoints from your installation or plugin source) from unknown IPs.
  • Requests that include unusual parameters like price, amount, discount, or order_meta modifications from unauthenticated sources.
• Suspicious scheduled tasks or hooks triggered around checkout (use WP­Crontrol or server logs to inspect).
• Presence of unknown admin users, changed passwords, or unexpected changes to plugin files (file modification timestamps).
• Web application firewall (WAF) alerts for requests attempting to set price-related parameters.

Collect logs and preserve them — if you suspect exploitation, you will need logs for investigation and potential law enforcement or payment processor interactions.

Immediate actions for site owners (short-term mitigations)

If your site runs Upsell Order Bump Offer for WooCommerce ≤ 3.1.4, take these immediate steps — prioritized:

1. Update the plugin to 3.1.5 (recommended)
   • The vendor has released a fix. Updating to 3.1.5 or later is the correct and fastest remediation.
2. If you cannot update immediately, do one of the following:
   • Deactivate the plugin temporarily to eliminate the attack surface.
   • Disable the order bump functionality within the plugin settings if that option is available.
   • Put checkout pages into maintenance mode or temporarily stop accepting orders until patched (extreme measure for stores with high risk).
3. Apply WAF rule(s)
   • Use your WAF (or a managed WordPress firewall) to block suspicious requests related to the plugin’s endpoints.
   • Block publicly visible endpoints that should be restricted to authenticated admin users.
   • Rate-limit requests to checkout-related endpoints to reduce automated exploitation.
4. Scan the site now
   • Run a full malware/indicator scan on WordPress files and the uploads directory.
   • Check for new PHP files, especially in writable directories. Look for web shells or scheduled tasks (cron).
5. Audit recent orders and refunds
   • Reconcile orders processed since the timeline of the vulnerability disclosure (you may need to check your date range from 9 May 2026 to present).
   • Flag suspicious orders and consider refund strategies or customer notifications as appropriate.
6. Credential hygiene
   • Reset admin passwords and API keys if you find evidence of suspicious activity.
   • Rotate any payment gateway credentials or API integrations if suspected compromise extends to external systems.
7. Preserve evidence
   • Save webserver logs, WordPress debug logs, and WAF logs to a secure location for investigation.

How WP­Firewall protects you while you patch

As a WordPress security vendor, WP­Firewall provides layered defenses that help mitigate this kind of risk:

• Managed WAF (basic plan): blocks common exploitation patterns and filters suspicious request payloads before they hit WordPress.
• Malware scanning: scans core, theme, and plugin files for unauthorized changes or backdoors after exploitation attempts.
• Mitigation of OWASP Top 10 risks: provides rules and protection coverage for common classes like broken authentication and input validation issues.
• Virtual patching (Pro/managed services): if you cannot immediately update, WP­Firewall can deploy a targeted virtual patch that blocks known exploit requests for this specific vulnerability at the edge — preventing abuse while you schedule maintenance.
• Rate limiting and IP controls: reduce automated mass scanning and exploitation attempts.
• Monitoring and alerts: notify you when suspicious patterns are detected (e.g., repeated attempts to hit plugin endpoints, sudden spikes in checkout POST requests).

If you haven’t done so, enabling managed WAF and continuous scanning will reduce the probability of successful exploitation while you update plugins.

Recommended medium-term remediation and testing

After you apply the patch, follow these steps to ensure full recovery and resilience:

1. Verify the update:
   • Confirm the plugin is updated to 3.1.5+ and check the plugin changelog for the applied fix.
   • Clear server and plugin caches (object cache, page cache, CDN).
2. Test checkout flows:
   • Perform test purchases (sandbox mode) to ensure order bump and checkout total calculations are correct.
   • Test with normal and with discount/coupon scenarios to ensure no unexpected price overrides occur.
3. Re-scan the site:
   • Perform another full malware scan after patching (files and database).
   • Inspect for backdoors that may have been placed earlier during exploitation.
4. Audit and reconcile:
   • Reconcile financial records and orders. Identify orders that could have been affected.
   • Contact affected customers and payment processors if necessary (follow applicable policies and law).
5. Harden plugin and site:
   • Restrict plugin management to strong admin accounts only. Limit plugin installation/update capability.
   • Remove unused plugins and themes — fewer plugins = smaller attack surface.
6. Set up automatic updates where safe:
   • Enable automatic updates for minor and security fixes where feasible. Ensure you have backups and staging to test major changes.
7. Add monitoring:
   • Enable change-detection on critical directories. Track file-modification alerts and admin-user creation.
8. Post-incident review:
   • Document what happened, timelines, and actions taken.
   • Update incident response playbooks to include this vulnerability class for the future.

What developers should fix (for plugin authors / integrators)

For plugin authors and developers working on checkout/price-related code, follow secure coding best practices to prevent broken authentication and price manipulation:

1. Enforce capability checks:
   • Any endpoint or action that changes plugin configuration, applies discount logic, or writes sensitive order meta must verify current_user_can() for appropriate capabilities.
   • Example: only allow manage_woocommerce or manage_options for admin-only operations.
2. Require and verify nonces:
   • For AJAX or form submissions originating from the admin area, require a nonce and verify it with wp_verify_nonce().
   • For REST endpoints, use permission_callback in register_rest_route().
3. Server-side validation and re-calculation:
   • Never trust client-submitted prices — always calculate final price server-side using product price, tax settings, coupons, and shipping logic.
   • Discard client-supplied price/amount fields (or treat them as suggestions only if validated and authorized).
4. Use prepared statements and strict sanitization:
   • Sanitize inputs and use type checks on numerical fields (floatval/absint) and whitelists for allowed values.
5. Avoid exposing sensitive endpoints:
   • Do not register publicly callable REST routes or AJAX actions that perform price/checkout changes without proper permission checks.
6. Logging and monitoring:
   • Log significant actions like price overrides, coupon creation, and order meta changes with context and user ID (or IP where user is unauthenticated).
7. Defensive programming:
   • Add fail-safe logic: if price calculations produce values outside expected minimums/maximums, log and reject.
8. Unit and integration tests:
   • Add automated tests to simulate unauthenticated and authenticated requests to endpoints to ensure unauthorized requests are blocked.

Example: secure REST route pattern (high-level)

Below is a high-level pattern demonstrating how a REST route permission check should look. This is illustrative — adapt to your plugin architecture.

register_rest_route( 'my-upsell-plugin/v1', '/set-bump-price', array(
  'methods'  => 'POST',
  'callback' => 'my_upsell_set_bump_price',
  'permission_callback' => function ( $request ) {
      // Only allow logged-in users with manage_woocommerce capability
      if ( ! is_user_logged_in() ) {
          return false;
      }
      return current_user_can( 'manage_woocommerce' );
  },
) );

function my_upsell_set_bump_price( WP_REST_Request $request ) {
    $price = $request->get_param( 'price' );
    // Validate price server-side
    $price = floatval( $price );
    if ( $price < 0 ) {
        return new WP_Error( 'invalid_price', 'Price must be non-negative', array( 'status' => 400 ) );
    }
    // Apply further checks and persistence
}

Key points:

• permission_callback prevents unauthenticated access.
• server-side validation enforces type and range.

Incident response playbook (step-by-step)

If you discover that a site was exploited via this vulnerability, follow a structured response:

1. Isolate and stabilize
   • Temporarily disable internet access for the site if possible.
   • Disable checkout flows and the vulnerable plugin to stop further abuse.
2. Preserve evidence
   • Make a full backup (file + DB) of the compromised state.
   • Export server logs, WAF logs, and access logs for the relevant timeframe.
3. Triage
   • Identify affected orders and customers; take steps to prevent further financial loss.
   • Check for added or modified admin users, changed plugin/theme files, or scheduled tasks.
4. Clean
   • Remove malicious files or revert to a clean backup taken before compromise.
   • Reinstall plugins/themes from original sources after verifying integrity.
5. Remediate
   • Apply the vendor patch (update plugin to 3.1.5+).
   • Fix any additional vulnerabilities found (weaker credentials, outdated core/themes, other vulnerable plugins).
6. Recover operations
   • Re-enable checkout only after thorough testing.
   • Reconcile orders and process necessary refunds or reimbursements.
7. Review and learn
   • Update security policy and tools.
   • Consider a professional review if persistent compromise is suspected.

Hardening checklist for WooCommerce stores (recommended baseline)

• Keep WordPress core, themes, and plugins updated.
• Remove unused plugins and themes.
• Enforce strong passwords and two-factor authentication for all admin users.
• Limit plugin install/update capability to a small set of trusted accounts.
• Use a managed WAF and malware scanner.
• Implement regular backups with offsite copies and retention.
• Routine security audits and change monitoring for file integrity.
• Use HTTPS and configure HSTS.
• Limit API and server access by IP where feasible.

Detection rules / WAF signatures (guidance for edge rules)

Since the vulnerability relies on missing authentication checks, an effective WAF rule strategy should be:

• Block POST requests to plugin endpoints that include price/amount parameters when not accompanied by a valid admin cookie and nonce header.
• Rate-limit repeated attempts from single IPs to checkout/upsell endpoints.
• Block suspicious parameter patterns like price=0 or price=0.00 when coupled with unauthenticated requests to bump endpoints.
• Notify and log any attempts that include parameters named “price”, “amount”, “discount”, “bump_price”, “order_meta” to the plugin endpoints if the request origin is unauthenticated.

Important: signature-based defenses must be tested to avoid false positives that block legitimate customers.

Recovery and financial reconciliation — practical points

• If you detect fraudulent orders:
  • Contact your payment processor immediately; they can help evaluate chargeback risk and fraud patterns.
  • Consider cancelling or refunding suspicious orders proactively.
  • Communicate with affected customers transparently if personally identifiable information was exposed.
• Retain an accurate timeline:
  • Note when the plugin version was updated, when the plugin was deactivated, and when the WAF/virtual patch was applied.
• For stores with heavy compliance obligations (PCI, GDPR, etc.), follow your breach-notification procedures and consult legal counsel when necessary.

Longer-term prevention strategies

• Adopt a defense-in-depth approach: secure hosting, WAF, monitoring, secure development lifecycle (SDLC) practices, and continuous scanning.
• Enforce a plugin approval process for your store or agency. Avoid installing plugins with low developer responsiveness or poor track records.
• Maintain a staging environment to test plugin updates before rolling them to production automatically.

Developer guidance for plugin maintainers (detailed)

If you’re a plugin maintainer or developer, the vulnerability shows why these practices matter:

• Use WordPress REST API’s permission_callback consistently.
• Never rely on client-side calculations for prices.
• Use WooCommerce API helpers for price math and tax calculations to ensure consistent server-side calculation.
• Implement an automated security test suite that simulates unauthenticated requests to every public endpoint and ensures expected access controls are in place.
• Perform security code reviews focused on authorization, input validation, and data sanitization.
• Offer security disclosure contact details and respond promptly to responsible reports.

How to respond if you discover this issue on a client site

1. Inform clients whose sites use the plugin and the affected versions immediately.
2. Schedule emergency maintenance windows to apply updates or disable the plugin.
3. Offer a reconciliation and forensic review service if compromise is suspected.
4. Document all actions in a client-friendly report.

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Final notes and recommended next steps (action plan)

1. Check plugin version now. If it is ≤ 3.1.4, update to 3.1.5 immediately.
2. If you cannot update right away, deactivate the plugin or disable its bump/upsell functionality until you can apply the patch.
3. Enable a managed WAF and malware scanner (basic protections can prevent mass exploitation).
4. Audit recent orders and logs for suspicious activity and preserve evidence.
5. Adopt the developer hardening and monitoring recommendations above.

This vulnerability is a reminder that plugins which touch checkout and pricing deserve extra scrutiny — both from plugin authors and WordPress site owners. If you need help triaging an incident, applying virtual patching, or implementing WAF rules tuned to WooCommerce, WP­Firewall’s team can assist with step­by­step mitigation and managed services.

Stay safe — and please update your installations now.