CVE-2026-76834Network attack vector

Unauthenticated object injection via negative integer keys

Published Sep 17, 2026 · Updated Sep 18, 2026

Deserialization in b2evolution CMS 6.7.8 through 7.2.5 allows remote attackers to instantiate arbitrary PHP objects via crafted POST requests. The param_check_serialized_array() validator fails to recognize object tokens following negative integer array keys, so htsrv/call_plugin.php passes the payload to unserialize(). No authentication or user interaction is required; code execution requires a suitable PHP POP gadget chain in the installation.

CVSS severity9.2
Critical
EPSS probability0.85%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Deserialization in b2evolution CMS 6.7.8 through 7.2.5 allows remote attackers to instantiate arbitrary PHP objects via crafted POST requests. The param_check_serialized_array() validator fails to recognize object tokens following negative integer array keys, so htsrv/call_plugin.php passes the payload to unserialize(). No authentication or user interaction is required; code execution requires a suitable PHP POP gadget chain in the installation.

The record

CVE
CVE-2026-76834
Published
Sep 17, 2026
Updated
Sep 18, 2026
Vendor
b2evolution
Product
b2evolution CMS
Classifications
CWE-502, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 17, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 18, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=6.7.8 <=7.2.5

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

b2evolution · b2evolution CMSversion=6.7.8 <=7.2.5

Published CVSS scores

8.1VulnCheckCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
9.2VulnCheckCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Activity data is delayed. The latest report is Sep 28, 2026.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-502Deserialization of Untrusted Data
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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