CVE-2026-33645 Fireshare has Path Traversal Arbitrary File Write in `/api/uploadChunked`
An authenticated attacker can write arbitrary files outside the intended directory via path traversal in the chunked upload endpoint, compromising system integrity.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-33645?
CVE-2026-33645 is a high-severity path traversal vulnerability in ShaneIsrael fireshare, published on 26 Mar 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
Fireshare facilitates self-hosted media and link sharing. In version 1.5.1, an authenticated path traversal vulnerability in Fireshare’s chunked upload endpoint allows an attacker to write arbitrary files outside the intended upload directory. The `checkSum` multipart field is used directly in filesystem path construction without sanitization or containment checks. This enables unauthorized file writes to attacker-chosen paths writable by the Fireshare process (e.g., container `/tmp`), violating integrity and potentially enabling follow-on attacks depending on deployment. Version 1.5.2 fixes the issue.
Which versions are affected by CVE-2026-33645?
It affects 1 product.
Products include Shaneisrael Fireshare.
How do I fix CVE-2026-33645?
No fix has been published for CVE-2026-33645 yet. Limit exposure of the affected software until one is available.
Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.
Is CVE-2026-33645 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-33645 exists.
Other vulnerabilities in ShaneIsrael fireshare
Sources
Also known as GHSA-7q8r-vpq3-89m7.