Fast Bundle Security Attack: What Happened and What to Do

Current status, checked August 3, 2026: Fast Bundle’s Shopify App Store listing is live again and presents an Install button. Fast Bundle says Shopify completed its review of both the incident report and the third-party penetration-test report, considers the security issue resolved on Fast Bundle’s side, and restored the app to limited visibility on July 30. Existing merchants can reinstall through the direct listing, and Fast Bundle says their previous bundle configurations will be restored.¹²

Key takeaways

• Fast Bundle says it detected a security attack on July 17, 2026, resolved the issue in its systems, and found no indication that customer, store, or shopper data was exposed.
• As of August 3, the official App Store listing is live again. Fast Bundle says existing merchants can reinstall manually and recover their previous bundle configurations.
• Fast Bundle has not publicly disclosed the attack method, affected-store count, technical indicators, or full third-party report.
• A theme-code scan can find suspicious or leftover storefront code, but it cannot inspect Fast Bundle’s servers or prove that no data was accessed.
• Preserve a copy of your theme and logs before removing anything. Test bundle pages, cart, discounts, and checkout now.

The Fast Bundle security attack has two parts for Shopify merchants: technical questions that have not been answered publicly and an immediate storefront problem.

Fast Bundle says a security attack was detected on July 17, 2026, and that Shopify then temporarily removed the app from the App Store and deactivated it for existing users as a precaution. In a public Shopify merchant thread, store owners reported missing offers and failed bundle purchases.²³

On July 27, Fast Bundle said Shopify had completed its review of both the incident report and the third-party Vulnerability Assessment and Penetration Testing report. Fast Bundle reported that Shopify considered the security issue resolved on its side and had started relisting the app.²

On July 30, Fast Bundle said Shopify restored the app to limited visibility, allowing the company to share a direct reinstall link with merchants. As of August 3, 2026, the official listing is live and presents an Install button. Fast Bundle says previous bundle configurations will be restored after reinstallation.¹²

Those are the vendor’s current findings and commitments. The incident report and penetration-test report have not been published, so merchants should separate Fast Bundle’s statements from what can be checked independently.

Why you can trust us

Jacques has more than 15 years of development experience, and we have spent over four years working inside Shopify themes for hundreds of merchants. We build Fudge, which reads a store’s real Liquid, JavaScript, CSS, templates, and theme-side app code, then prepares any approved changes in a draft theme.

This is not a forensic report on Fast Bundle. It is a plain-English reading of the public incident record and a practical checklist for the parts of your own store you can inspect.

What happened in the Fast Bundle security attack?

Here is the public timeline from Fast Bundle’s incident page.²

Fast Bundle says Shopify completed its review of both the incident report and the separate third-party Vulnerability Assessment and Penetration Testing report. Neither report is public.

That distinction matters. “The issue is resolved,” “the app is approved to return,” and “every question about the incident has a public answer” are three different statements.

The non-technical explanation

Think of a Shopify app as a specialist contractor with keys to specific rooms.

A bundle app may need access to products, discounts, cart behaviour, orders, and storefront code so it can build the offer and make it work at checkout. If the app provider’s own systems are attacked, Shopify can disconnect the app while the provider investigates.

Disconnecting the contractor reduces possible harm. It can also switch off the work your store depends on. That is why a security response can turn into missing bundle widgets, broken offers, or an app that appears uninstalled.

This does not mean Shopify itself was breached. It also does not prove that every Fast Bundle merchant received malicious code or lost data.

Fast Bundle has not publicly disclosed:

• The initial access method or vulnerability
• Which system or component was affected
• Who carried out the attack
• Whether unauthorized code reached any merchant theme
• The number of affected stores
• The time window of any possible exposure
• File names, domains, hashes, or other indicators merchants could search for
• The contents of the third-party incident report

Public Reddit posts have repeated a claim that malicious code could be injected. Fast Bundle’s official disclosure does not confirm that technical detail. Treat it as an unverified merchant claim, not the established explanation of the incident.

Was customer data exposed?

Fast Bundle says its investigation and security testing found no indication that customer, store, or shopper data was accessed, exposed, or leaked.²

That is reassuring, but the correct wording is “Fast Bundle says it found no indication.” The third-party report and supporting evidence are not public.

A theme-code audit cannot settle this question. Storefront code is only one layer. It cannot see what happened inside an app provider’s database, server logs, cloud accounts, or internal tools.

It helps to separate three kinds of risk:

1. Availability: offers stop working. This is the clearest merchant impact reported publicly.
2. Integrity: unauthorized code changes what a storefront does. No public primary source has established that this happened to Fast Bundle merchants.
3. Confidentiality: store or customer information is viewed or copied without permission. Fast Bundle says it found no indication of this, but its evidence is not public.

What should Fast Bundle merchants do now?

1. Preserve evidence before editing

Duplicate or download your live theme. Save the incident emails, app status, screenshots, timestamps, and any unusual storefront behaviour.

If you find something suspicious later, a clean copy of the original state is more useful than a theme that has already been tidied.

2. Reinstall only from the official listing

If you decide to return to Fast Bundle, reinstall it only through the official Shopify App Store listing. Confirm that the listing names Fast Bundle as the developer, then check that your expected bundles and settings have returned before sending traffic back to them.¹

Fast Bundle says previous bundle configurations will be restored. Treat that as something to verify on your own store, not a reason to skip testing.²

3. Test the buying path

Check:

• Every bundle landing page and product page
• Add to cart and cart drawer
• Bundle pricing and automatic discounts
• Discount-code combinations
• Checkout on mobile and desktop
• Different currencies and markets
• Subscription bundles
• Order line items, inventory, and 3PL output

Pause ads that lead to a broken offer. Send that traffic to a working product or collection page until the bundle path passes.

4. Review the app state and recent activity

In Shopify admin, open Settings > Apps and review Fast Bundle’s install history, permissions, and recent activity where available. Shopify says the app details screen can show which areas a third-party app could view or edit and the date of recent requests.⁴

Also review all store activity history available to you, especially the days before and after July 17, for unfamiliar users, apps, product edits, discounts, or theme changes. July 17 is the detection date, not a confirmed exposure start. Account logs have limits, but an unexpected change with a relevant timestamp is worth escalating to Shopify Support.

5. Audit a duplicate theme

Search for:

• References to fastbundle.co
• fast_bundle_service
• fast_bundle_service.liquid
• product.fastbundle.json
• content_for_header contains 'fastbundle.co'
• {% render 'fast_bundle_service' %}
• Unfamiliar remote JavaScript
• Encoded or heavily obfuscated code
• Unexpected redirects or form listeners
• Recent changes to cart and add-to-cart files
• App snippets that remain but are no longer used

Fast Bundle’s own uninstall guide names the fast_bundle_service snippet and product.fastbundle.json template as files its older installation path could add.⁵

Finding one of those files does not mean it is malicious. It may be normal Fast Bundle code or harmless residue. The point of the scan is to identify what exists, what still runs, and what needs a human decision.

6. Do not blindly delete code

Shopify warns that some apps add code to a theme that is not removed automatically when the app is uninstalled.⁶ Modern theme app extension blocks are removed automatically, while older direct edits can remain.⁷

Work on a duplicate theme. For every proposed deletion, document:

• The exact file and lines
• What the code loads
• Whether another file calls it
• What changes when it is disabled
• How cart and checkout behave afterward

If you expect to reinstall Fast Bundle, deleting its normal integration files may make recovery harder. Get store-specific guidance from Fast Bundle before removing confirmed app code.

7. Verify any replacement app

Fast Bundle has warned about similarly named apps that are not affiliated with it. Check the developer name, listing URL, permissions, privacy policy, and migration steps before installing anything.²

If you need bundles back now, our comparison of Fast Bundle alternatives ranks replacements by individual SKU handling, bundle types, fulfilment, and migration effort.

What Fudge can scan

Fudge’s theme-code investigation can read your real Shopify theme and report observable facts such as:

• A specific script or snippet exists in a specific file
• A theme loads code from an unfamiliar domain
• A block contains obfuscated JavaScript, redirects, or runtime code execution
• Fast Bundle files remain after uninstall
• A particular app snippet is a likely cause of a cart error, which can then be tested by disabling it in a draft
• A file differs from a supplied or available trusted theme copy
• A proposed fix can be tested safely in a draft theme

Fudge can also inspect the bundle implementation and help rebuild it in native code through the Shopify storefront editor. For related cleanup steps, see how to remove leftover app code from Shopify.

What a Fudge scan cannot prove

A theme-only scan cannot tell you:

• Whether Fast Bundle’s backend was compromised
• Whether customer data was accessed or copied
• The attacker, root cause, or full incident scope
• What happened in Shopify’s internal systems
• What happened in app-owned databases or server logs
• Whether a credential or session token was stolen
• The contents of checkout extensions, Shopify Functions, custom pixels, tag managers, app proxies, or remote scripts unless they are separately included in the review
• That the store is completely secure because no suspicious file was found

The accurate result after a clean scan is:

No suspicious theme-code indicators were found within the files and checks included in this point-in-time scan.

It is not:

Your store was not affected.

That limit is not a weakness in the scan. It is the boundary between a storefront code review and a full incident investigation.

Prompt: ask Fudge to audit your theme

Copy this prompt into Fudge:

Run a read-only audit of my published Shopify theme for suspicious or leftover third-party app code after the Fast Bundle incident. Do not change or publish anything. Review Liquid, JavaScript, JSON templates, app embeds, app blocks, Custom Liquid, script references, and remote domains. Search for fastbundle, fast-bundle, fastbundle.co, fast_bundle_service, fast_bundle_service.liquid, and product.fastbundle.json, plus unfamiliar or obfuscated scripts, eval, new Function, encoded payloads, unexpected redirects, and form listeners. Where theme version history or a trusted baseline is available, flag recently changed cart and add-to-cart files. For every finding, give the exact file and line, what the code does, why it appears suspicious or benign, a confidence level, and a safe next step. Treat Fast Bundle attribution markers as normal app code unless there is separate evidence that they are harmful. Separate confirmed findings from items that only need review. End by stating that this theme-only audit does not inspect checkout extensions, Shopify Functions, custom pixels, tag managers, app proxies, remote code contents, app servers, databases, or private logs unless separately included in scope.

If your offers disappeared and you want help mapping the old setup, tell us what you were running in the Fudge community.

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