Mirasvit Full Page Cache Warmer: code execution flaw under attack

What is affected

Mirasvit Full Page Cache Warmer is mostly run by companies, schools and public bodies, not on home computers. You are unlikely to have it yourself, but organisations that hold your data may. Breaches that start with flaws like this one are how personal data ends up leaked.

Mirasvit Full Page Cache Warmer contains a deserialization of untrusted data vulnerability that could allow unauthenticated attackers to achieve remote code execution by supplying a crafted serialized PHP object in the CacheWarmer cookie.

What an attacker can do

This is a code execution flaw. It lets an attacker run their own commands or programs on the affected system. In practice that usually means taking it over: installing malware, stealing data or using it to reach other devices on the same network.

How it is reached

Over the internet or network

Access the attacker needs

No account needed

Does the victim have to do something?

No, works without the victim doing anything

What to do

1. At home: nothing to install. Keep your own devices updated and use a different password for every service, so that a breach at one organisation does not open your other accounts.
2. If you administer Mirasvit Full Page Cache Warmer at work: apply the vendor's fix or mitigation now and review logs for signs of compromise, because the flaw was being exploited before it was listed.
3. If the product is past its support date and no fix exists, take it off the internet or retire it.

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Vendor advisories and fixes

• mirasvit.commirasvit.com/package/changelog/?package=mirasvit/module-cache-warmer

How urgent is it

CISA added this vulnerability to its Known Exploited Vulnerabilities catalogue on June 3, 2026, which means there is reliable evidence of attacks in the wild. US federal agencies must fix it by June 6, 2026, a deadline that has already passed. That deadline does not bind anyone else, but it shows how seriously the agency rates it.

The EPSS model estimates a 2.1% probability that this flaw will be exploited somewhere in the next 30 days. That is higher than 81% of all scored vulnerabilities.

Its CVSS severity score is 9.3 out of 10 (critical), as recorded in the US National Vulnerability Database.

Technical description

Mirasvit Full Page Cache Warmer for Magento 2 before version 1.11.12 contains a PHP object injection vulnerability that allows unauthenticated attackers to achieve remote code execution by supplying a crafted serialized PHP object in the CacheWarmer cookie. Attackers can exploit the unrestricted call to PHP's native unserialize() function combined with gadget chains available in Magento and its dependencies to execute arbitrary code on the server.