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VulnerabilityPublished

CVE-2026-34838: Intermesh groupoffice · Deserialization of Untrusted Data

Affects Intermesh groupofficeSource CVE Database V5

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Not known to be exploited · CVSS 10.0 Critical · fixed in 26.0.12 : patch Intermesh groupoffice as a priority.

Data as of 29 Oct 2026, 19:04 UTC

CVSS 3.1 base score
10.0Critical
How severe the flaw is on the 0–10 CVSS scale.
EPSS
1.0% chance of exploitation in 30 days – higher than 63% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 26.0.12, 25.0.90, 6.8.156
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 2 Apr 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: evidence found.

    Public exploit code: GitHub proofs of concept

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), GitHub proofs of concept, the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.

What to do

Upgrade groupoffice and intermesh/groupoffice to 26.0.12, 25.0.90 or 6.8.156.

Affected software

ProductAffectedFixed in
IntermeshgroupofficeAffected
  • <26.0.12
Fixed in
  • 26.0.12
IntermeshgroupofficeAffected
  • <25.0.90
Fixed in
  • 25.0.90
IntermeshgroupofficeAffected
  • <6.8.156
Fixed in
  • 6.8.156
GitHubintermesh/groupofficepkg:github/intermesh/groupofficeOther threatsAffected
  • <6.8.156
  • <25.0.90
  • <26.0.12
Fixed in
  • 6.8.156
  • 25.0.90
  • 26.0.12

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

This vulnerability has been officially patched in Group-Office versions 6.8.156, 25.0.90, and 26.0.12. Users should upgrade to these or later versions to remediate the issue. No additional mitigations are specified or required once patched.

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.

References

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