CVE-2026-76834 b2evolution CVE debrief

Who should care

System administrators and security teams using b2evolution CMS versions 6.7.8 through 7.2.5 should assess exposure and prioritize patching or mitigation. The vulnerability has a CVSS score of 9.2 and is considered critical. Verification of affected versions and scope is required.

Why it matters

CVE-2026-76834 is a critical vulnerability in b2evolution CMS that allows unauthenticated code execution. System administrators and security teams should assess exposure and prioritize patching or mitigation.

• Potential code execution if suitable POP gadget chains exist
• Unauthenticated attackers can submit crafted serialized PHP objects
• Verification of affected versions and scope is required

Technical summary

The vulnerability is caused by an incomplete fix for CVE-2016-8901 in b2evolution CMS versions 6.7.8 through 7.2.5. The serialized-array object check in param_check_serialized_array() fails to reject payloads with negative integer array keys, allowing unauthenticated attackers to submit crafted serialized PHP objects via POST requests to htsrv/call_plugin.php. This could potentially lead to code execution if suitable POP gadget chains exist. The CVE record and NVD entry provide details on the vulnerability, but verification of affected versions and scope is required.

Defensive priority

High priority for systems using b2evolution CMS versions 6.7.8 through 7.2.5

Recommended defensive actions

• Verify b2evolution CMS version and apply patches if necessary
• Restrict access to htsrv/call_plugin.php
• Monitor for suspicious POST requests
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record and NVD entry provide details on the vulnerability. However, the exact scope of affected systems and versions requires verification from official sources. The vulnerability is caused by an incomplete fix for CVE-2016-8901 in b2evolution CMS versions 6.7.8 through 7.2.5. The serialized-array object check in param_check_serialized_array() fails to reject payloads with negative integer array keys, allowing unauthenticated attackers to submit crafted serialized PHP objects via POST requests to htsrv/call_plugin.php. The CVV

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.