PatchSiren

PatchSiren cyber security CVE debrief

CVE-2026-54194 ThemeFusion CVE debrief

A critical vulnerability, CVE-2026-54194, has been discovered in Fusion Builder versions up to 3.15.4. This vulnerability allows unauthenticated attackers to inject malicious PHP objects, potentially leading to arbitrary code execution. With a CVSS score of 9.8, this vulnerability is considered critical and requires immediate attention. The vulnerability was published on June 17, 2026, and has since been modified on the same day. Users of Fusion Builder should take immediate action to mitigate this vulnerability.

Vendor
ThemeFusion
Product
Fusion Builder
CVSS
CRITICAL 9.8
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-17
Original CVE updated
2026-06-17
Advisory published
2026-06-17
Advisory updated
2026-06-17

Who should care

Administrators and users of Fusion Builder versions up to 3.15.4 should be aware of this critical vulnerability and take immediate action to mitigate it. This vulnerability can be exploited by unauthenticated attackers, making it a high-risk issue.

Technical summary

CVE-2026-54194 is a PHP object injection vulnerability in Fusion Builder versions up to 3.15.4. This vulnerability allows attackers to inject malicious PHP objects, which can lead to arbitrary code execution. The vulnerability has a CVSS score of 9.8 and is considered critical. The CVSS vector is CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H, indicating that the vulnerability can be exploited over the network with low attack complexity and no privileges required.

Defensive priority

high

Recommended defensive actions

  • Update Fusion Builder to version 3.15.5 or later
  • Restrict access to the Fusion Builder plugin
  • Monitor for suspicious activity
  • Implement a web application firewall (WAF)
  • Use secure coding practices
  • Regularly update and patch plugins and software
  • Perform security audits and vulnerability assessments

Evidence notes

The vulnerability was reported by Patchstack and is documented in the CVE record. The CVE record and NVD detail provide additional information about the vulnerability.

Official resources

public