Vulnerability · Published Apr 2, 2026 · Assigned by GitHub_M

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

Critical 10.0

In plain English

A critical-severity unsafe deserialization in groupoffice from Intermesh. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 1.0% (higher than 64% of all known vulnerabilities). Ready-made attack tooling exists: public proof-of-concept code.

Severity (CVSS 3.1)10.0Critical

Exploit odds (30 days)1.0%top 35.8% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack tooling1Public PoC

Official 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 (as reported)

Vendor	Product	Versions
Intermesh	groupoffice	< 6.8.156< 25.0.90< 26.0.12

Weakness: CWE-502 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

References

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