CVE-2026-34838
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 · uneditedGroup-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.
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 confidenceA deserialization vulnerability in Group-Office's AbstractSettingsCollection model allows authenticated attackers to inject a serialized FileCookieJar object into settings, achieving arbitrary file write and direct RCE.
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< 6.8.156>= 25.0.1, < 25.0.90>= 26.0.1, < 26.0.12CVSS 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
- Changed
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/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 checksWork through these to decide whether this CVE applies to you.
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Identify Group-Office installation versionLocate the version file or admin panel that displays the installed Group-Office version. Common locations include the admin dashboard, a version.php file in the installation root, or the package metadata.Affected if The installed version falls into one of these ranges: < 6.8.156, >= 25.0.1 but < 25.0.90, or >= 26.0.1 but < 26.0.12.
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Confirm settings module is activeVerify that the AbstractSettingsCollection model is in use. This model is typically part of core Group-Office functionality and handles application settings storage.Affected if The settings module or AbstractSettingsCollection model is loaded and used by the application.
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Inspect settings storage for serialized data patternsExamine the database tables or configuration files where settings are stored. Look for unusual serialized PHP objects, particularly any instances containing 'FileCookieJar' or similar cookie jar class references.Affected if Serialized PHP objects or FileCookieJar references are found in settings storage areas, indicating potential injection.
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Audit web directory for unauthorized PHP file creationSearch the web root and subdirectories for newly created PHP files that were not part of the original installation, especially in writable directories such as uploads, cache, or tmp folders.Affected if Unexpected PHP files exist in the web directory that were not intentionally deployed.
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Review authentication and settings change logsCheck application and web server logs for authenticated users modifying settings, particularly in bulk or containing base64-encoded or serialized payloads.Affected if Logs show settings modifications with unusual payload patterns from authenticated user accounts.
You are affected if your Group-Office version is below 6.8.156, between 25.0.1-25.0.89, or between 26.0.1-26.0.11, and the application settings functionality is accessible to authenticated users.
Generated from the published advisory. Verify against your own configuration.
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 · scoped6.8.15625.0.9026.0.12
Upgrade to patched versions 6.8.156, 25.0.90, or 26.0.12; if patching is delayed, restrict authenticated access and monitor for anomalous setting modifications.
6.8.156 (6.x branch), 25.0.90 (25.x branch), or 26.0.12 (26.x branch)
- 1. Identify the currently installed Group Office version by checking the system configuration or administration panel
- 2. Determine which version branch you are on (6.x, 25.x, or 26.x)
- 3. For 6.x branch: Upgrade to version 6.8.156 or later
- 4. For 25.x branch (versions 25.0.1-25.0.89): Upgrade to version 25.0.90 or later
- 5. For 26.x branch (versions 26.0.1-26.0.11): Upgrade to version 26.0.12 or later
- 6. After upgrade, verify the AbstractSettingsCollection model has been patched and no longer accepts serialized PHP objects in settings
- 7. Review user permissions and consider limiting access to settings modification after patching
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation3.0 h
- Implementation6.0 h
- Testing3.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,984.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-34838 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-34838 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- 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
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