Critical severity · published Apr 2, 2026
CVE-2026-34838
Group-Office: Authenticated Remote Code Execution via PHP Insecure Deserialization in `AbstractSettingsCollection`
9.9
CVSS
1%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Changed
Exploitation
Is it being used?
Exploit prediction (EPSS)1.0% · higher than 63% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
GR
groupoffice · Intermesh
< 6.8.156; < 25.0.90; < 26.0.12 · source: vendor
GR
Group-office · Intermesh
before 6.8.156; 25.0.1 before 25.0.90; 26.0.1 before 26.0.12 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-34838
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-34838
Release Notes
https://github.com/Intermesh/groupoffice/releases/tag/v25.0.90
Release Notes
https://github.com/Intermesh/groupoffice/releases/tag/v26.0.12
Release Notes
https://github.com/Intermesh/groupoffice/releases/tag/v6.8.156
Vendor Advisory
https://github.com/Intermesh/groupoffice/security/advisories/GHSA-h22j-frrf-5vxq
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