CVE-2026-41034
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 · uneditedONLYOFFICE DocumentServer before 9.3.0 has an untrusted pointer dereference in XLS processing/conversion (via pictFmla.cbBufInCtlStm and other vectors), leading to an information leak and ASLR bypass.
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 confidenceONLYOFFICE DocumentServer before version 9.3.0 contains an untrusted pointer dereference vulnerability in the XLS file processing and conversion module (specifically in pictFmla.cbBufInCtlStm and related code paths). This memory corruption issue allows attackers to read sensitive information from process memory and bypass ASLR protection, potentially facilitating more severe follow-on attacks.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
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
- Changed
- Confidentiality
- Low
- Integrity
- None
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:N/A:N
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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Verify ONLYOFFICE DocumentServer installationCheck for ONLYOFFICE DocumentServer by querying installed packages (e.g., dpkg -l | grep -i onlyoffice, rpm -qa | grep -i onlyoffice, or check /opt/onlyoffice directory existence)Affected if ONLYOFFICE DocumentServer is not installed on the system
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Determine installed versionRun: documentserver --version, or check /usr/bin/documentserver --version, or inspect package version via dpkg/rpm queryAffected if The installed version is lower than 9.3.0 (e.g., 9.2.x, 9.1.x, 9.0.x, or any version below 9.3.0)
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Identify XLS processing moduleVerify the XLS conversion module exists by checking for x2t or other conversion binaries in /opt/onlyoffice/documentserver/server/DocService or similar paths, and confirm the pictFmla.cbBufInCtlStm code path is present in the binariesAffected if XLS file processing module is present and the version is vulnerable
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Confirm service exposure to XLS inputsReview configuration files in /etc/onlyoffice/documentserver or the web interface to determine if the conversion service accepts XLS file uploads from users or external sourcesAffected if The service accepts XLS file uploads or conversion requests from untrusted sources without additional filtering
A system is affected if ONLYOFFICE DocumentServer is installed with a version lower than 9.3.0 and the XLS processing module is exposed to user-supplied XLS files.
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.
From vendor dataUpgrade ONLYOFFICE DocumentServer to version 9.3.0 or later to obtain the patched code. If immediate upgrading is not feasible, restrict untrusted XLS file uploads and convert operations through input validation or network segmentation as a temporary compensating control.
- Consultation3.0 h
- Implementation4.0 h
- Testing6.0 h
- Review / QA3.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-41034 — 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-2026-41034 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
- No spam, self-promotion, credentials, or personal data