# CVE-2026-63266: Arbitrary file write via calcext:data-mappings, sql provider and Firebird backup functionality

> An attacker can write arbitrary files to any user-writable location by crafting a LibreOffice Calc document with a malicious Firebird database link.

- **Severity:** Medium 6.8 (`CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 5 Oct 2026
- **Updated:** 5 Oct 2026
- **Also known as:** DEBIAN-CVE-2026-63266, ECHO-c6b4-711f-c38e, GHSA-5436-5r9x-m4jv, MINI-6xrr-hxr3-w4qj, UBUNTU-CVE-2026-63266

## What is CVE-2026-63266?

CVE-2026-63266 is a medium-severity path traversal vulnerability in The Document Foundation LibreOffice, published on 5 Oct 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

### Official description

LibreOffice Calc can link a cell range to an external data source, and the link is saved in the document. Through such a link a document could open an embedded Firebird database that wrote a file to any location the user could write to. In fixed versions an embedded Firebird database can open or create files only inside its own private directory.

Weakness: CWE-22 (Improper Limitation of a Pathname to a Restricted Directory)

## Which versions are affected by CVE-2026-63266?


## How do I fix CVE-2026-63266?

Apply the vendor's patch.

## Is CVE-2026-63266 being exploited?

There is no known exploitation of CVE-2026-63266 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-63266 and fix it if it is affected.

What it is: CVE-2026-63266 is a medium-severity path traversal vulnerability in The Document Foundation LibreOffice, published on 5 Oct 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-63266 in the wild and no public exploit code.

Affected product: The Document Foundation LibreOffice. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-63266/ (Markdown: https://insights.sbomify.com/CVE-2026-63266/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-63266
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-63266
- OSV: https://osv.dev/vulnerability/CVE-2026-63266

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-63266/
Summaries are generated and may contain mistakes; the official description above is the record.