Deserialization in Intermesh Group-Office
CVE-2026-34838
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.
Vulnerability class: Insecure Deserialization
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.9 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.010 (62.0th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 62nd percentile — 62.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.010 · newest: 0.010 · change: -0.000
Affected products
- Intermesh Group-Office
- Intermesh Groupoffice — versions < 6.8.156, < 25.0.90, < 26.0.12
Weakness classification (CWE)
Public proof-of-concept exploits
References
- github.com/Intermesh/groupoffice/security/advisories/GHSA-h22j-frrf-5vxq (Vendor Advisory)
- github.com/Intermesh/groupoffice/releases/tag/v25.0.90 (Release Notes)
- github.com/Intermesh/groupoffice/releases/tag/v26.0.12 (Release Notes)
- github.com/Intermesh/groupoffice/releases/tag/v6.8.156 (Release Notes)
Frequently asked questions
- What is CVE-2026-34838?
- CVE-2026-34838 is a critical-severity vulnerability in Intermesh Group-Office, classified under Deserialization of Untrusted Data. CVSS score: 9.9/10. Published 2026-04-02.
- How severe is CVE-2026-34838?
- Critical severity. CVSS v3 base score is 9.9 out of 10.
- Is CVE-2026-34838 known to be exploited?
- 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.