Ollama up to 0.17.5 on Windows Update code download

Summaryinfo

A vulnerability, which was classified as problematic, was found in Ollama up to 0.17.5 on Windows. This impacts an unknown function of the component Update Handler. The manipulation results in code download. This vulnerability was named CVE-2026-42249. The attack may be performed from remote. There is no available exploit.

Detailsinfo

A vulnerability, which was classified as problematic, was found in Ollama up to 0.17.5 on Windows. Affected is some unknown functionality of the component Update Handler. The manipulation with an unknown input leads to a code download vulnerability. CWE is classifying the issue as CWE-494. The product downloads source code or an executable from a remote location and executes the code without sufficiently verifying the origin and integrity of the code. This is going to have an impact on integrity. CVE summarizes:

Ollama for Windows contains a Remote Code Execution vulnerability in its update mechanism due to improper handling of attacker‑controlled HTTP response headers. When downloading updates, the application constructs local file paths using values derived from HTTP headers without validation. These values are passed directly to filepath.Join, allowing path traversal sequences (../) to be resolved and enabling files to be written outside the intended update staging directory. An attacker who can influence update responses can exploit this flaw to write arbitrary executables to attacker‑chosen locations accessible to the current user, including the Windows Startup directory. This allows execution of arbitrary executables. Critically, when chained with CVE‑2026‑42248 (Missing Signature Verification for Updates), an attacker can deliver malicious payloads that are written to sensitive locations and executed automatically. Because Ollama for Windows performs silent automatic updates and executes staged binaries without user interaction, this results in automatic and persistent code execution without user awareness. Maintainers of this project were notified early about this vulnerability, but didn't respond with the details of vulnerability or vulnerable version range. Versions from 0.12.10 to 0.17.5 were tested and confirmed as vulnerable, other versions were not tested but might also be vulnerable.

The weakness was presented by Bartłomiej Dmitruk. The advisory is available at cert.pl. This vulnerability is traded as CVE-2026-42249 since 04/25/2026. The exploitability is told to be difficult. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. The technical details are unknown and an exploit is not available. This vulnerability is assigned to T1495 by the MITRE ATT&CK project.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-26211). If you want to get best quality of vulnerability data, you may have to visit VulDB.

Productinfo

Name

• Ollama

Version

• 0.17.0
• 0.17.1
• 0.17.2
• 0.17.3
• 0.17.4
• 0.17.5

CPE 2.3info

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CPE 2.2info

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If you want to get best quality of vulnerability data, you may have to visit VulDB.

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