# CVE-2026-42249: Ollama for Windows path traversal in update mechanism

Source: https://junglewise.ai/threats/cve-2026-42249-ollama-for-windows-path-traversal-in-update-mechanism  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-04-29. Updated: 2026-05-18  
License: CC BY 4.0 with a link back

CVE-2026-42249 · Severity: critical · CVSS 9.8 · Published 2026-04-29

Ollama for Windows, a tool used to run large language models locally, contains a flaw in how it handles software updates. An attacker who can intercept or manipulate the update process can remotely install and run malicious software on a user's computer. Because the application updates silently in the background, this can lead to a permanent and hidden compromise of the system without any user interaction.

## Quick answers

**Is CVE-2026-42249 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-42249 being exploited in the wild.

**How severe is CVE-2026-42249?** Critical severity, with a CVSS score of 9.8, published 29 April 2026.

**Which products and versions are affected?** Ollama Ollama for Windows 0.12.10 to 0.17.5 (confirmed).

**Is there a fix for CVE-2026-42249?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-42249 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-42249?** Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A path traversal vulnerability exists in the Ollama for Windows update mechanism due to the improper use of 'filepath.Join' with unvalidated HTTP response headers. An attacker capable of influencing update responses (e.g., via Man-in-the-Middle or DNS poisoning) can inject '../' sequences to write arbitrary files outside the intended staging directory. When chained with CVE-2026-42248 (which bypasses signature verification on Windows), an attacker can write malicious executables to sensitive locations like the Windows Startup directory. Since Ollama performs silent automatic updates and executes staged binaries without user interaction, this leads to persistent remote code execution. Tested vulnerable versions range from 0.12.10 to 0.17.5.

## Affected products

- Ollama Ollama for Windows 0.12.10 to 0.17.5 (confirmed)

## Timeline

- 2026-04-29: advisory: Initial disclosure by CERT Polska
- 2026-04-29: disclosed: CVE-2026-42249 published

## References

- [https://cert.pl/en/posts/2026/04/CVE-2026-42248/](https://cert.pl/en/posts/2026/04/CVE-2026-42248/)
- [https://ollama.com/](https://ollama.com/)