Quick answers
- Is CVE-2026-82238 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-82238 being exploited in the wild.
- How severe is CVE-2026-82238?
- Low severity, with a CVSS score of 3.1, published 28 August 2026.
- Which products and versions are affected?
- Filebrowser >= 2.24.0, <= 2.63.23.
- Is there a fix for CVE-2026-82238?
- No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
- How is CVE-2026-82238 attacked?
- It is attacked over the network.
- Am I affected by CVE-2026-82238?
- Check whether you run Filebrowser at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
The vulnerability is a time-of-check time-of-use (TOCTOU) race condition in the TUS PATCH upload handler (http/tus_handlers.go:237–291). The handler checks if file.Size matches the declared Upload-Offset, then opens the file in append mode and writes the request body. However, multiple concurrent PATCH requests at the same offset all observe file.Size == 0 and pass the conflict check before any write completes, allowing each to append their full body to the file. The resulting file can be N× the declared Upload-Length for N concurrent requests. Exploitation requires network access and authentication with create permission. No serialization, mutex, or offset tracking exists in the stat→check→write window. The project is no longer maintained and no fix will ship; workarounds include rate-limiting or serializing PATCH requests at a reverse proxy.
Affected products
- filebrowser filebrowser >= 2.24.0, <= 2.63.23
Timeline
- 2026-08-28: disclosed: Security advisory published
- 2026-08-31: other: Project archived by owner