CVE-2025-66959Public exploitNetwork attack vector

Server crash via unchecked GGUF string length

Published Jan 21, 2026 · Updated Jan 21, 2026

Denial of service in the GGUF decoder in Ollama 0.12.10 allows remote attackers to crash the server via a crafted model file. The readGGUFString function treats an untrusted 64-bit metadata length as a slice size without a maximum bound or overflow check, causing a Go runtime panic. Exploitation requires unauthenticated access to the blob-upload and model-creation API endpoints and terminates the Ollama server process.

CVSS severity7.5
High
EPSS probability4.73%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in the GGUF decoder in Ollama 0.12.10 allows remote attackers to crash the server via a crafted model file. The readGGUFString function treats an untrusted 64-bit metadata length as a slice size without a maximum bound or overflow check, causing a Go runtime panic. Exploitation requires unauthenticated access to the blob-upload and model-creation API endpoints and terminates the Ollama server process.

The record

CVE
CVE-2025-66959
Published
Jan 21, 2026
Updated
Jan 21, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-20, CWE-400, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 21, 2026CVE publishedPublication date reported by the CVE source.
  2. Jan 21, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.5CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-20Improper Input Validation
CWE-400Uncontrolled Resource Consumption
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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