Remote Code Execution in Ollama via Update Mechanism
Summary
| CVE | CVE-2026-42249 |
|---|---|
| State | PUBLISHED |
| Assigner | CERT-PL |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-04-29 12:16:19 UTC |
| Updated | 2026-04-29 12:16:19 UTC |
| Description | 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. |
Risk And Classification
Primary CVSS: v4.0 7.7 HIGH from [email protected]
CVSS:4.0/AV:A/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:L/SI:L/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Problem Types: CWE-22 | CWE-494 | CWE-494 CWE-494: Download of Code Without Integrity Check | CWE-22 CWE-22 Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 4.0 | [email protected] | Secondary | 7.7 | HIGH | CVSS:4.0/AV:A/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:L/SI:L/SA:L/E:X/C... |
| 4.0 | CNA | CVSS | 7.7 | HIGH | CVSS:4.0/AV:A/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:L/SI:L/SA:L |
CVSS v4.0 Breakdown
Attack Vector
AdjacentAttack Complexity
HighAttack Requirements
PresentPrivileges Required
NoneUser Interaction
NoneConfidentiality
HighIntegrity
HighAvailability
HighSub Conf.
LowSub Integrity
LowSub Availability
LowCVSS:4.0/AV:A/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:L/SI:L/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Vendor Declared Affected Products
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| cert.pl/en/posts/2026/04/CVE-2026-42248 | [email protected] | cert.pl | |
| ollama.com | [email protected] | ollama.com | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: Bartłomiej Dmitruk (striga.ai) (en)
There are currently no legacy QID mappings associated with this CVE.