# CVE-2026-32759: File Browser TUS Negative Upload-Length Fires Post-Upload Hooks Prematurely > Authenticated users can trigger premature upload completion via negative length, enabling DoS or command execution if exec hooks are enabled. - **Severity:** Medium 5.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:L/SC:N/SI:L/SA:L`) - **Exploited in the wild:** Not known - **Login needed:** Any signed-in user - **Attackable:** Over the internet - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 19 Mar 2026 - **Updated:** 9 Jun 2026 - **Also known as:** GHSA-ffx7-75gc-jg7c, GO-2026-4713 ## What is CVE-2026-32759? CVE-2026-32759 is a medium-severity vulnerability in filebrowser, published on 19 Mar 2026. Any signed-in user can exploit it over the network, with no action from the victim. ### Official description File Browser is a file managing interface for uploading, deleting, previewing, renaming, and editing files within a specified directory. In versions on the 2.x branch prior to 2.33.8, the TUS resumable upload handler parses the Upload-Length header as a signed 64-bit integer without validating that the value is non-negative, allowing an authenticated user to supply a negative value that instantly satisfies the upload completion condition upon the first PATCH request. This causes the server to fire after_upload exec hooks with empty or partial files, enabling an attacker to repeatedly trigger any configured hook with arbitrary filenames and zero bytes written. The impact ranges from DoS through expensive processing hooks, to command injection amplification when combined with malicious filenames, to abuse of upload-driven workflows like S3 ingestion or database inserts. Even without exec hooks enabled, the negative Upload-Length creates inconsistent cache entries where files are marked complete but contain no data. All deployments using the TUS upload endpoint (/api/tus) are affected, with the enableExec flag escalating the impact from cache inconsistency to remote command execution. This feature has been disabled by default for all installations from v2.33.8 onwards, including for existent installations. To exploit this vulnerability, the instance administrator must turn on a feature and ignore all the warnings about known vulnerabilities. Weakness: CWE-190 (Integer Overflow or Wraparound) ## Which versions are affected by CVE-2026-32759? 4 open source packages ship an affected version, including github.com/filebrowser/filebrowser/v2 and github.com/filebrowser/filebrowser. It affects 1 product. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `github.com/filebrowser/filebrowser/v2` | Go | All versions | None | | `github.com/filebrowser/filebrowser/v2` | Go | All versions | 2.33.8 | | `github.com/filebrowser/filebrowser/v2` | Go | All versions | 2.33.8 | | `github.com/filebrowser/filebrowser` | Go | All versions | None | Products: Filebrowser Filebrowser. ## How do I fix CVE-2026-32759? Upgrade github.com/filebrowser/filebrowser/v2 to 2.33.8 or later. ## Is CVE-2026-32759 being exploited? There is no known exploitation of CVE-2026-32759 in the wild and no public exploit code. ## Other vulnerabilities in filebrowser - [CVE-2026-32760](https://insights.sbomify.com/CVE-2026-32760/): File Browser Self Registration Grants Any User Admin Access When Default Permissions Include Admin (critical 10.0) - [CVE-2026-29188](https://insights.sbomify.com/CVE-2026-29188/): File Browser: TUS Delete Endpoint Bypasses Delete Permission Check (critical 9.1) - [CVE-2023-39612](https://insights.sbomify.com/CVE-2023-39612/): Cross-site scripting in n/a (critical 9.0) - [CVE-2026-30934](https://insights.sbomify.com/CVE-2026-30934/): FileBrowser Quantum: Stored XSS in public share page via unsanitized share metadata (text/template misuse) (high 8.9) - [CVE-2021-46398](https://insights.sbomify.com/CVE-2021-46398/): Cross-Site Request Forgery in Filebrowser (high 8.8) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2026-32759 and fix it if it is affected. What it is: CVE-2026-32759 is a medium-severity vulnerability in filebrowser, published on 19 Mar 2026. Any signed-in user can exploit it over the network, with no action from the victim. Exploitation: There is no known exploitation of CVE-2026-32759 in the wild and no public exploit code. Affected packages and fixed versions: - github.com/filebrowser/filebrowser/v2 (Go): affected all versions; no fix listed - github.com/filebrowser/filebrowser/v2 (Go): affected all versions; fixed in 2.33.8 - github.com/filebrowser/filebrowser/v2 (Go): affected all versions; fixed in 2.33.8 - github.com/filebrowser/filebrowser (Go): affected all versions; no fix listed 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-2026-32759/ (Markdown: https://insights.sbomify.com/CVE-2026-32759/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2026-32759 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-32759 - OSV: https://osv.dev/vulnerability/CVE-2026-32759 --- From sbomify Insights: https://insights.sbomify.com/CVE-2026-32759/ Summaries are generated and may contain mistakes; the official description above is the record.