CVE-2025-15514
Unknown Unknown - Not Provided
Null Pointer Dereference in Ollama Image Processing Causes DoS

Publication date: 2026-01-12

Last updated on: 2026-01-12

Assigner: VulnCheck

Description
Ollama 0.11.5-rc0 through current version 0.13.5 contain a null pointer dereference vulnerability in the multi-modal model image processing functionality. When processing base64-encoded image data via the /api/chat endpoint, the application fails to validate that the decoded data represents valid media before passing it to the mtmd_helper_bitmap_init_from_buf function. This function can return NULL for malformed input, but the code does not check this return value before dereferencing the pointer in subsequent operations. A remote attacker can exploit this by sending specially crafted base64 image data that decodes to invalid media, causing a segmentation fault and crashing the runner process. This results in a denial of service condition where the model becomes unavailable to all users until the service is restarted.
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Meta Information
Published
2026-01-12
Last Modified
2026-01-12
Generated
2026-06-16
AI Q&A
2026-01-13
EPSS Evaluated
2026-06-15
NVD
CVE-2025-15514
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
ollama ollama to 0.13.5 (inc)
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-395 Catching NullPointerException should not be used as an alternative to programmatic checks to prevent dereferencing a null pointer.
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Executive Summary

This vulnerability is a null pointer dereference in Ollama versions 0.11.5-rc0 through 0.13.5 affecting the multi-modal model image processing functionality. When the application processes base64-encoded image data via the /api/chat endpoint, it does not verify if the decoded data is valid media before passing it to the function mtmd_helper_bitmap_init_from_buf. This function can return NULL for malformed input, but the code does not check for this before dereferencing the pointer, leading to a crash. [2]

Impact Analysis

A remote attacker can exploit this vulnerability by sending specially crafted base64 image data that decodes to invalid media, causing a segmentation fault that crashes the runner process. This results in a denial of service (DoS) condition where the model becomes unavailable to all users until the service is restarted. [2]

Detection Guidance

This vulnerability can be detected by monitoring for crashes or segmentation faults in the Ollama runner process, especially after receiving base64-encoded image data via the /api/chat endpoint. Network detection could involve inspecting traffic for suspicious or malformed base64 image data sent to the /api/chat endpoint. Specific commands are not provided in the resources. [2]

Mitigation Strategies

Immediate mitigation steps include restarting the Ollama service if it crashes due to this vulnerability. Additionally, restricting or validating input to the /api/chat endpoint to prevent malformed base64 image data from being processed can help reduce risk. Since the vulnerability remains unresolved as of the advisory date, monitoring for updates or patches from Ollama is recommended. [2]

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