filebrowser up to 2.61.2 TUS Upload Endpoint /api/tus after_upload integer overflow

Summaryinfo

A vulnerability identified as problematic has been detected in filebrowser up to 2.61.2. Affected by this issue is the function after_upload of the file /api/tus of the component TUS Upload Endpoint. This manipulation causes integer overflow. This vulnerability appears as CVE-2026-32759. The attack may be initiated remotely. There is no available exploit.

Detailsinfo

A vulnerability has been found in filebrowser up to 2.61.2 and classified as problematic. Affected by this vulnerability is the function after_upload of the file /api/tus of the component TUS Upload Endpoint. The manipulation with an unknown input leads to a integer overflow vulnerability. The CWE definition for the vulnerability is CWE-190. The product performs a calculation that can produce an integer overflow or wraparound, when the logic assumes that the resulting value will always be larger than the original value. This can introduce other weaknesses when the calculation is used for resource management or execution control. As an impact it is known to affect integrity, and availability. The summary by CVE is:

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.

The advisory is shared at github.com. This vulnerability is known as CVE-2026-32759 since 03/13/2026. The exploitation appears to be easy. The attack can be launched remotely. Technical details are known, but no exploit is available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 06/09/2026).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Name

• filebrowser

Version

• 2.61.0
• 2.61.1
• 2.61.2

Website

• Product: https://github.com/filebrowser/filebrowser/

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Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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