What’s Vulnerable › Vulnerabilities

CVE-2026-34838: Group-Office: Authenticated Remote Code Execution via PHP Insecure Deserialization in `AbstractSettingsCollection`

• Severity: critical (CVSS 9.9 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.0% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-04-02 · updated 2026-07-24
• Weakness: CWE-502

Description

Group-Office is an enterprise customer relationship management and groupware tool. Prior to versions 6.8.156, 25.0.90, and 26.0.12, a vulnerability in the AbstractSettingsCollection model leads to insecure deserialization when these settings are loaded. By injecting a serialized FileCookieJar object into a setting string, an authenticated attacker can achieve Arbitrary File Write, leading directly to Remote Code Execution (RCE) on the server. This issue has been patched in versions 6.8.156, 25.0.90, and 26.0.12.

Affected products

• Intermesh Group-Office: before 6.8.156; from 25.0.1 before 25.0.90; from 26.0.1 before 26.0.12 — fixed in 25.0.90, 26.0.12, 6.8.156

How to fix

Upgrade to a fixed version: Intermesh Group-Office 25.0.90, 26.0.12, 6.8.156. Check the vendor advisory for mitigations.

References

• https://github.com/Intermesh/groupoffice/releases/tag/v25.0.90
• https://github.com/Intermesh/groupoffice/releases/tag/v26.0.12
• https://github.com/Intermesh/groupoffice/releases/tag/v6.8.156
• https://github.com/Intermesh/groupoffice/security/advisories/GHSA-h22j-frrf-5vxq

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