The flaw exists because the Windows version of Ollama performs no verification of the authenticity or integrity of downloaded update executables. The verification routine always returns success, so any unsigned or tampered executable is treated as a valid update, staged, and executed by the application. This enables an attacker to supply a malicious update package that will be installed without user intervention, leading to arbitrary code execution on the affected system.

Ollama for Windows versions from 0.12.10 through 0.17.5 have been confirmed vulnerable; earlier and later releases were not tested and may also be affected. The issue is specific to the Windows implementation; other platform variants of Ollama are not impacted.

The CVSS score of 7.7 indicates a high severity vulnerability. Because the update mechanism is silent and automatic, an attacker can deliver a malicious executable to a user with unsigned update handling, causing execution without user awareness. The EPSS score of <1% indicates a very low exploitation probability; however, based on the description, it is inferred that if an attacker can host a malicious update, the application would accept and execute it. The vulnerability is not listed in the CISA KEV catalog. The lack of signature verification allows an attacker-controlled update source to inject executable payloads, so the risk remains high for Windows users running Ollama in the vulnerable version range.