Fireshare facilitates self-hosted media and link sharing. Prior to version 1.5.3, the fix for CVE-2026-33645 was applied to the authenticated /api/uploadChunked endpoint but was not applied to the unauthenticated /api/uploadChunked/public endpoint in the same file (app/server/fireshare/api.py). An unauthenticated attacker can exploit the checkSum parameter to write arbitrary files with attacker-controlled content to any writable path on the server filesystem. This issue has been patched in version 1.5.3.
Exploitability
AV:NAC:LPR:NUI:NScope
S:UImpact
C:NI:HA:H9.1/CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:HInput Validation