dbcve.org
Group OfficeApplication · Intermesh

CVE-2026-27947

HIGH · 8.8 CVSS v3.1 Published 2026-02-27
Fix available
A fix is available. Upgrade to 6.8.154 / 25.0.87 or later.
See remediation →
94/100
Remediation priority · Urgent
Remotely reachable Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Group-Office is an enterprise customer relationship management and groupware tool. Versions prior to 26.0.9, 25.0.87, and 6.8.154 have an authenticated Remote Code Execution vulnerability in the TNEF attachment processing flow. The vulnerable path extracts attacker-controlled files from `winmail.dat` and then invokes `zip` with a shell wildcard (`*`). Because extracted filenames are attacker-controlled, they can be interpreted as `zip` options and lead to arbitrary command execution. Versions 26.0.9, 25.0.87, and 6.8.154 fix the issue.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Group-Office versions prior to 26.0.9, 25.0.87, and 6.8.154 contain an authenticated RCE in TNEF attachment processing. The vulnerability arises when extracting files from winmail.dat attachments - the code invokes zip with a shell wildcard using attacker-controlled filenames, allowing malicious filenames to be interpreted as zip options and execute arbitrary commands.

MitigationUpgrade Group-Office to version 26.0.9, 25.0.87, or 6.8.154 (depending on your current major version branch). This patch addresses the TNEF processing vulnerability by properly sanitizing extracted filenames before invoking zip.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Group OfficeApplication
Affected:< 6.8.154>= 25.0.1, < 25.0.87>= 26.0.1, < 26.0.9

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify installed Group-Office version
    Query the Group-Office installation for its version number through the admin interface, package manager, or version file specific to the installation method
    Affected if The installed version is below 6.8.154, or between 25.0.1 and 25.0.86 inclusive, or between 26.0.1 and 26.0.8 inclusive
  2. Confirm TNEF attachment processing is active
    Determine whether Group-Office is configured to process or extract TNEF (winmail.dat) attachments from incoming emails, as this is the required attack vector
    Affected if TNEF/winmail.dat attachment extraction is enabled in the mail processing configuration
  3. Verify user authentication is enabled
    Confirm that user accounts and authentication mechanisms are functional in the Group-Office instance
    Affected if User authentication is available and operational, which is required for the authenticated RCE to be exploitable

You are affected if your installed Group-Office version falls within the vulnerable ranges AND TNEF attachment processing is enabled AND user authentication is active in your environment.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 6.8.154 / 25.0.87 / 26.0.9 or later
Fixed in 6.8.15425.0.8726.0.9
Interim mitigation

Upgrade Group-Office to version 26.0.9, 25.0.87, or 6.8.154 (depending on your current major version branch). This patch addresses the TNEF processing vulnerability by properly sanitizing extracted filenames before invoking zip.

Recommended fix Moderate confidence

Upgrade to 6.8.154 (for 6.x), 25.0.87 (for 25.x), or 26.0.9 (for 26.x) depending on your current major version branch

  1. 1. Create a complete backup of the Group Office installation including database and files
  2. 2. Identify your current Group Office version in the admin interface or via system check
  3. 3. If running version 6.x: upgrade to version 6.8.154 or later
  4. 4. If running version 25.x: upgrade to version 25.0.87 or later
  5. 5. If running version 26.x: upgrade to version 26.0.9 or later
  6. 6. After upgrade, clear any caches and verify the TNEF/winmail.dat processing functionality works correctly
  7. 7. Confirm the upgrade was successful by checking the version number in the admin panel
Caveat Review release notes for your specific version branch for any breaking changes or migration requirements before upgrading

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Group Office Scoped from the published advisory
  • Consultation3.0 h
  • Implementation5.0 h
  • Testing4.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,460
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,936.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2026-27947 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-27947 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data