CVE-2025-66959
Published: 21 January 2026
Summary
CVE-2025-66959 is a high-severity Improper Input Validation (CWE-20) vulnerability in Ollama Ollama. Its CVSS base score is 7.5 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Application or System Exploitation (T1499.004); ranked in the top 47.2% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
Threat & Defense at a Glance
Threat & Defense Details
Likely Mitigating ControlsAI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Security testing and evaluation at multiple SDLC stages directly detects missing or flawed input validation, with the required remediation process ensuring fixes are applied.
Spam protection mechanisms perform filtering and detection on inbound/outbound messages, directly compensating for missing or weak input validation of unsolicited content.
Limiting concurrent sessions directly prevents uncontrolled resource consumption by capping the number of active sessions per user or account.
Analysis identifies uncontrolled resource consumption indicative of denial-of-service or abuse attempts.
Contingency plan testing includes resource exhaustion scenarios to verify recovery, making it harder for attackers to sustain exploits that cause uncontrolled consumption.
Updated contingency plans include current procedures to detect, contain, and recover from resource exhaustion, limiting an attacker's ability to sustain impact from uncontrolled consumption.
Alternate site allows resumption of operations if resource exhaustion at the primary site is exploited to cause unavailability.
Alternate telecommunications services enable resumption of essential functions when primary services become unavailable due to uncontrolled resource consumption.
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Remote exploitation of input validation flaw in GGUF decoder directly enables application/system crash for denial of service (T1499.004).
NVD Description
An issue in ollama v.0.12.10 allows a remote attacker to cause a denial of service via the GGUF decoder
Deeper analysisAI
CVE-2025-66959 is a denial-of-service vulnerability in Ollama version 0.12.10, published on 2026-01-21. The flaw exists in the GGUF decoder and is classified under CWE-20 (Improper Input Validation) and CWE-400 (Uncontrolled Resource Consumption). It carries a CVSS v3.1 base score of 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H), indicating high severity due to its potential for significant availability impact.
A remote, unauthenticated attacker can exploit the vulnerability over the network with low attack complexity and no user interaction required. By crafting malicious input targeting the GGUF decoder, the attacker triggers a denial of service, such as a panic or crash, disrupting service availability without compromising confidentiality or integrity.
Mitigation details are available in the referenced advisories, including the Ollama GitHub issue at https://github.com/ollama/ollama/issues/9820 and the technical analysis at https://zero.shotlearni.ng/blog/cve-2025-66959panic-dos-via-unchecked-length-in-gguf-decoder-copy/. Security practitioners should consult these for patch information and recommended updates.
Details
- CWE(s)