CVE-2020-11535
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 · uneditedAn issue was discovered in ONLYOFFICE Document Server 5.5.0. An attacker can craft a malicious .docx file, and exploit XML injection to enter an attacker-controlled parameter into the x2t binary, to rewrite this binary and/or libxcb.so.1, and execute code on a victim's server.
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 Document Server 5.5.0 contains an XML injection vulnerability in its document parsing functionality. Attackers can embed malicious payloads in .docx files that are processed by the x2t binary, allowing path traversal to overwrite the x2t binary itself or the libxcb.so.1 library, leading to arbitrary code execution on the server.
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= 5.5.0CVSS 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
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/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 checksWork through these to decide whether this CVE applies to you.
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Confirm installed ONLYOFFICE Document Server versionRun the command to check the installed version of ONLYOFFICE Document Server (commonly: dpkg -l | grep onlyoffice-documentserver or rpm -qa | grep onlyoffice)Affected if The installed version is exactly 5.5.0
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Locate the x2t binarySearch for the x2t binary in the ONLYOFFICE installation directory, typically found under /var/www/onlyoffice/Data/files/converter or similar paths within the Document Server hierarchyAffected if The x2t binary exists and is present in the expected conversion directory
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Verify document conversion service is enabledCheck if the document conversion service is active and processing .docx files (inspect running processes for x2t or converter worker processes)Affected if The conversion service is running and processing document files
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Check integrity of x2t binary and libxcb.so.1Compare the file hashes (md5sum/sha256sum) of the x2t binary and libxcb.so.1 library against known-good baseline values, or check file modification timestampsAffected if The x2t binary or libxcb.so.1 shows unexpected modification timestamps or hash mismatches from the original installation
A user is affected if they have ONLYOFFICE Document Server version 5.5.0 running with the document conversion service enabled, particularly if the x2t binary or libxcb.so.1 shows signs of tampering.
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 Document Server to a patched version. Additionally, inspect the server for any signs of compromise (modified binaries) and consider implementing file integrity monitoring for critical binaries.
- Consultation2.0 h
- Implementation4.0 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 $3,088.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2020-11535 — 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-2020-11535 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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