This is an urgent message to anyone managing an Adobe Commerce or Magento Open Source-based online store. According to a security bulletin APSB26-05 published by Adobe Commerce on March 10, 2026, several major issues have been found in almost any existing active version of the solution. This is not only a routine fix or update. We are referring to problems which give hackers an opportunity to get complete access to your store. 

As for the current situation, Adobe confirmed no active exploitation. But the window of opportunity for attackers is rapidly decreasing. Once such a security bulletin is issued, they start deciphering what has been fixed and searching for vulnerable installations almost immediately after. 

What’s next? You will find out all you need to know about APSB26-05 in this article. 

What Is APSB26-05 and Why Does It Matter? 

The name of the security bulletin issued by Adobe concerning the vulnerabilities in Adobe Commerce and Magento Open Source software is APSB26-05. Since these vulnerabilities are rated critically important in the context of Adobe, we can say that their impact level for users is very high, while their exploitability level is moderate. 

If your store remains unpatched, attackers can potentially: 

• Bypass your security controls entirely, opening hidden entry points into your store 

• Escalate their privileges from limited access to full administrator-level control 

• Execute unauthorized code on your server, allowing them to install malware or create hidden backdoors 

• Steal customer data including personal information, contact details, and purchase history 

• Skim payment information at checkout without any visible signs of tampering 

• Take your store offline or hold it hostage through ransomware 

The most dangerous part is not the attack itself  it is how silently it happens. Most store owners do not discover a breach when it occurs. They discover it weeks later, when customers report fraud, Google flags the site for malware, or a third-party audit catches traces of the intrusion. By then, the damage is already done. 

Which Versions Are Affected? 

This bulletin covers a wide range of versions. Check your store against the list below. 

Adobe Commerce affected versions: 2.4.9-alpha3, 2.4.8-p3, 2.4.7-p8, 2.4.6-p13, 2.4.5-p15, 2.4.4-p16 and all earlier releases in each branch. 

Adobe Commerce B2B affected versions: 1.5.3-alpha3, 1.5.2-p3, 1.4.2-p8, 1.3.5-p13, 1.3.4-p15, 1.3.3-p16 and all earlier releases in each branch. 

Magento Open Source affected versions: 2.4.9-alpha3, 2.4.8-p3, 2.4.7-p8, 2.4.6-p13, 2.4.5-p15 and all earlier releases in each branch. 

If your store is running a version older than 2.4.4 such as Magento 2.3.x your situation is even more urgent. Those versions are past end-of-life and receive no security patches at all, including this one. A full version upgrade is the only real solution. 

What Should You Update To? 

Adobe has released specific patched versions for every affected branch. The upgrade path is a direct step to the next patch release. 

B2B module users should apply the corresponding patch for their branch simultaneously with the core Commerce update. 

The Right Way to Apply This Patch 

This is where most mistakes happen. Store owners either delay patching because they fear breaking something, or they rush it directly to production and something does break. Both outcomes are avoidable. 

The correct process is: 

1. Back up everything first. Full database backup and complete file backup before any changes. No exceptions, no shortcuts.
2. Apply the patch in a staging environment. Never patch your live store first. Set up a copy of your store, apply the patch there, and test it thoroughly.
3. Test every critical function. After patching in staging, check your checkout flow, payment gateways, product pages, admin functions, and any custom features or third-party extensions your store depends on.
4. Resolve any conflicts before going live. If an extension or custom module breaksin staging, fix it there. Going to production with known conflicts is not acceptable. 
5. Schedulea productiondeployment during low-traffic hours. Have a rollback plan ready before you start. Apply the patch, verify everything works, then close the maintenance window. 

Patching is not what breaks stores. Rushing the process without testing is what breaks stores. 

Why Delaying This Is a Business Risk, Not Just a Technical One 

The most common reason store owners delay patches is the fear of compatibility issues. That concern is valid but the cost comparison is not even close. 

Applying this patch costs you hours of controlled, planned development work. A data breach costs you legal liability under GDPR and PCI-DSS, regulatory fines that can reach up to 4% of annual revenue, lost customer trust that does not come back, Google penalties that suppress your search rankings for months, and remediation costs that far exceed what prevention would have cost. 

There is no version of this calculation where delaying the patch is the safer choice. The risk of patching is manageable. The risk of not patching is not. 

How Cosmonaut Can Help 

Applying a security patch on a live Magento store with custom development and third-party extensions requires someone who knows what they are doing. Cosmonaut’s Magento development team handles this as a structured, low-risk process. 

We cover the full process end to end: 

• Assess your current version and confirm the correct patch path 

• Apply the patch in a staging environment with full compatibility testing 

• Resolve any extension or custom code conflicts before touching production 

• Deploy to your live store during a scheduled maintenance window with a rollback plan in place 

• Verify everything is working correctly after deployment and confirm your patch status in writing 

If your store is running an end-of-life version that is not covered by this bulletin, we handle full Magento version upgrades as well safely, without data loss, and with your customizations intact. 

We also offer ongoing Magento support and maintenance plans, so you are never in a reactive position with security bulletins again. You get patch monitoring, timely application, and a team that already knows your store. 

Conclusion 

APSB26-05 is one of the most serious security bulletins Adobe has released for Magento in recent years. It covers critical vulnerabilities privilege escalation, security bypass, unauthorized code execution across nearly every version of Adobe Commerce and Magento Open Source currently in active use. 

The patch is available. The fix is known. The only question is whether you act before an attacker does. 

Check your version today. If you are on an affected release, get the patch applied  properly, with staging testing, not directly to production. 

Cosmonaut is ready to handle it for you. Contact our team and we will assess your store and get it secured quickly.