CVE-2026-34745
criticalFireshare 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.
9.1
cvss
critical
common vulnerability scoring system v3.1. measures intrinsic severity on a 0-10 scale.
epss
0.0009
kev
no
cisa known exploited vulnerabilities catalog. confirmed active exploitation.
CVSS 3.1
Common Vulnerability Scoring System v3.1
9.1
/ 10
CRITICAL
exploitability
Attack Vector
Network
Attack Vector (AV:N): exploitable remotely over the network — most dangerous. no physical or adjacent access needed.
Attack Complexity
Low
Attack Complexity (AC:L): no special conditions needed. attack can be reliably reproduced.
Privileges Required
None
Privileges Required (PR:N): no authentication needed. any anonymous attacker can exploit this.
User Interaction
None
User Interaction (UI:N): no victim action needed. fully exploitable without user interaction.
impact
Scope
Unchanged
Scope (S:U): impact limited to the vulnerable component.
Confidentiality
None
Confidentiality (C:N): no confidentiality impact.
Integrity
High
Integrity (I:H): complete data modification possible. attacker can modify any data.
Availability
High
Availability (A:H): total denial of service. attacker can fully shut down the resource.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
activity density
rdintel assessment
composite score from 15+ signals including exploitation status, epss probability, detection coverage, and community attention. 0-100 scale.
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