CVE-2026-32759
Filebrowser integer overflow
- Published19 Mar 2026
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.
CVSS 3.1 breakdown
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:HAffected products
Remediation
No fixed version is recorded in the NVD data. Check the vendor advisory for the latest guidance.
References
Related CVEs
Recent high-severity vulnerabilities sharing a weakness type.
Frequently asked
Is CVE-2026-32759 being actively exploited?
CVE-2026-32759 is not in the CISA KEV catalog. A public exploit reference exists, so treat it as exploitable. Its EPSS exploit probability is 2.17%.
How severe is CVE-2026-32759?
CVE-2026-32759 has a CVSS 3.1 base score of 8.1, rated high. EPSS estimates a 2.17% probability of exploitation.
Which products are affected by CVE-2026-32759?
Affected products include Filebrowser.
How do I fix CVE-2026-32759?
Apply the vendor's patch or advisory guidance, then verify no affected versions remain across your devices.
How Secuno handles this
Secuno correlates vulnerabilities like CVE-2026-32759 against the real software inventory on every managed device, as each hourly inventory arrives. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.
Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.