CVE-2025-66959 is a vulnerability identified in the ollama software version 0.12.10, specifically within its GGUF decoder component. The issue allows a remote attacker to cause a denial of service (DoS) condition by exploiting improper input validation or resource management flaws, classified under CWE-400 (Uncontrolled Resource Consumption) and CWE-20 (Improper Input Validation). The vulnerability can be triggered remotely without any authentication or user interaction, making it relatively easy to exploit. The attack results in a crash or hang of the ollama application, impacting its availability. The CVSS v3.1 base score is 7.5, reflecting a high severity due to the network attack vector (AV:N), low attack complexity (AC:L), no privileges required (PR:N), and no user interaction (UI:N). The scope remains unchanged (S:U), and only availability is impacted (A:H), with confidentiality and integrity unaffected. No patches or mitigations have been officially released yet, and no known exploits have been observed in the wild. The vulnerability poses a risk to systems running ollama, particularly those exposed to untrusted networks or processing untrusted GGUF data inputs. Organizations using ollama should prepare for remediation once patches become available and consider interim protective measures.

For European organizations, the primary impact of CVE-2025-66959 is on service availability. Systems running ollama that process GGUF data could be remotely crashed, leading to downtime and disruption of business operations, especially in AI-driven environments or software development workflows relying on ollama. While confidentiality and integrity are not directly compromised, the denial of service could affect critical services or delay time-sensitive processes. Industries such as technology, research, and AI development in Europe could face operational interruptions. Additionally, organizations with exposed network services running vulnerable versions of ollama are at higher risk. The lack of known exploits reduces immediate threat but does not eliminate risk, especially as attackers may develop exploits once the vulnerability is public. The impact is heightened in countries with significant AI infrastructure or where ollama adoption is higher, potentially affecting national competitiveness and service reliability.

1. Monitor official ollama channels and security advisories closely for the release of patches addressing CVE-2025-66959 and apply them promptly. 2. Restrict network access to systems running ollama, especially blocking untrusted external traffic to GGUF decoder services. 3. Implement network-level protections such as firewalls and intrusion prevention systems to detect and block malformed GGUF data packets. 4. Employ input validation and filtering mechanisms where possible to prevent malformed or malicious GGUF data from reaching the decoder. 5. Consider isolating ollama instances in segmented network zones to limit the blast radius of a potential DoS attack. 6. Conduct regular availability and stress testing to detect abnormal behavior indicative of exploitation attempts. 7. Develop incident response plans specific to denial of service scenarios involving ollama to minimize downtime. 8. Engage with vendors or community forums for workarounds or unofficial patches if available before official fixes are released.