CVE-2026-34838Public exploitNetwork attack vector

Authenticated code execution via unsafe settings deserialization

Published Apr 2, 2026 · Updated Apr 2, 2026

Insecure deserialization in Intermesh BV GroupOffice before 6.8.156, 25.0.90, or 26.0.12 allows remote authenticated users to execute code. The _loadData method passes serialized setting values to PHP unserialize without blocking class creation, letting a FileCookieJar destructor write a PHP web shell to an attacker-chosen path. Any low-privileged account can reach core/saveSetting; the resulting code runs as the web application process and can compromise server data and availability.

CVSS severity9.9
Critical
EPSS probability1.03%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Insecure deserialization in Intermesh BV GroupOffice before 6.8.156, 25.0.90, or 26.0.12 allows remote authenticated users to execute code. The _loadData method passes serialized setting values to PHP unserialize without blocking class creation, letting a FileCookieJar destructor write a PHP web shell to an attacker-chosen path. Any low-privileged account can reach core/saveSetting; the resulting code runs as the web application process and can compromise server data and availability.

The record

CVE
CVE-2026-34838
Published
Apr 2, 2026
Updated
Apr 2, 2026
Vendor
Intermesh BV
Product
GroupOffice
Classifications
CWE-502, T1505.003, T1190
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

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

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=< 25.0.90
  2. Affected versionversion=< 26.0.12
  3. Affected versionversion=< 6.8.156

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Intermesh BV · GroupOfficeversion=< 25.0.90; version=< 26.0.12; version=< 6.8.156

Published CVSS scores

9.9GitHubCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

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.

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

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-502Deserialization of Untrusted Data
T1505.003Web Shell
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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