GHSA-jh9g-8jqw-m2qx CVE-2026-45351 PYSEC-2026-2741
Open WebUI Exposes System Prompt to Regular User [Non-Admin]
- Severity
- 6.5 / 10
- Medium · CVSS 3.1
- Exploit chance (EPSS)
- 0.28%
- Chance of exploitation in the next 30 days. Higher than 20.68% of scored vulnerabilities.
- Known exploited
- No
- Not in CISA's catalog
- Weakness
- CWE-200 Exposure of Sensitive Information to an Unauthorized Actor
- Fix
0.8.9- Upgrade open-webui to this version or later
Description
Summary
A regular user [non-admin] can view the system prompt of the model which is set by an admin.
Details
When a regular user [non-admin] logs into the application, a http://IP:8080/api/models? web request is initiated by the application and in response, it reveals the system prompt of available models set by admin on models pages in workspace affecting the confidentiality of application
Affected System
Open WebUI v0.6.40 "main" branch
Vulnerability Details and Advisory from OWASP
LLM07:2025 System Prompt Leakage - https://genai.owasp.org/llmrisk/llm072025-system-prompt-leakage/
PoC
1. Regular User [Non-Admin] login on Open WebUI application. 2. A series of web requests get generated by the application, and the http://IP:8080/api/models? is also gets generated by application . 3. The response of http://IP:8080/api/models? web request reveals the system prompt of all the available models which is set is by the admin on models pages in workspace. <img width="940" height="352" alt="system prompt leak" src="https://github.com/user-attachments/assets/bd2c76f1-398f-4bc8-a8b2-5e14a768c560" />
Web Request
GET /api/models? HTTP/1.1 Host: localhost:8080 sec-ch-ua-platform: "Linux" authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpZCI6IjdmYjUxMmFhLTBmMTAtNDRkZi1iOWY1LThmNDg2MWFhNWFmOCIsImV4cCI6MTc2NjU2MjE5OH0.yJpavBynKItPQv76SMGKK012JIf29PVUv9sjuCDuRGQ Accept-Language: en-US,en;q=0.9 sec-ch-ua: "Chromium";v="141", "Not?A_Brand";v="8" sec-ch-ua-mobile: ?0 User-Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/141.0.0.0 Safari/537.36 Accept: application/json Content-Type: application/json Sec-Fetch-Site: same-origin Sec-Fetch-Mode: cors Sec-Fetch-Dest: empty Referer: http://localhost:8080/ Accept-Encoding: gzip, deflate, br Cookie: token=eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpZCI6IjdmYjUxMmFhLTBmMTAtNDRkZi1iOWY1LThmNDg2MWFhNWFmOCIsImV4cCI6MTc2NjU2MjE5OH0.yJpavBynKItPQv76SMGKK012JIf29PVUv9sjuCDuRGQ Connection: keep-alive
Impact
1. System prompts can reveal the model instructions, providing an attackers with inside knowledge about the system capabilities and bypass restrictions. 2. Attacker can perform content manipulation affecting the input/output of the model.
Details from MITRE ATLAS
Discover LLM System Information - https://atlas.mitre.org/techniques/AML.T0069 Discover LLM System Information: System Instruction Keywords - https://atlas.mitre.org/techniques/AML.T0069.001 Discover LLM System Information: System Prompt - https://atlas.mitre.org/techniques/AML.T0069.002
Recommendation
1. The web response should not reveal system prompt and related internal/back-end details regarding the model to the regular user. 2. Only the model name and non-sensitive details should be revealed to regular user and internal/back-end details should not be disclosed.
Affected versions
PyPI
| Package | Vulnerable | Fixed in |
|---|---|---|
| open-webui | < 0.8.9 |
0.8.9 |
How to fix
Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.
open-webui PyPI → 0.8.9
- pip
pip install --upgrade "open-webui>=0.8.9"- poetry
poetry add "open-webui>=0.8.9"- uv
uv add "open-webui>=0.8.9"
Severity breakdown
CVSS 3.1 6.5
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- None
- Availability
- None
Weakness
CWE-200: Exposure of Sensitive Information to an Unauthorized Actor
The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.
How to prevent it
- Architecture and Design: Compartmentalize the system to have "safe" areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area. Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.
References
Advisories
Packages
Other links
Timeline
- Published
- Last updated by the source
- Latest EPSS score
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| GHSA-wvm9-9g5j-623f Open WebUI: Users denied by the OAuth role policy can still sign in via token exchange | Medium | Also affects open-webui |
| GHSA-4qg5-cxx4-g927 Open WebUI: Users denied by the OAuth domain allowlist or role policy can still sign in via token exchange | Medium | Also affects open-webui |
| GHSA-jqhh-cjmq-vmv6 Open WebUI: Any authenticated user can hang the server via a cyclic chat message history | Medium | Also affects open-webui |
| GHSA-5x7x-4c3c-qf5w Open WebUI: Server-side fetches reach blocked and internal hosts via unvalidated HTTP redirect targets | Medium | Also affects open-webui |
| GHSA-3cgp-3cqx-j8w2 Open WebUI: Any authenticated user can hang the server via message deletion in a cyclic chat tree | Medium | Also affects open-webui |
| GHSA-34r3-9m95-vq73 Open WebUI: Any authenticated user can reach the Azure platform channel via server-side web fetch | High | Also affects open-webui |
| GHSA-2724-6cpj-gf3v Open WebUI: Non-admin users can delete admin-owned external knowledge connections via knowledge base deletion | High | Also affects open-webui |
| GHSA-3pf7-q2g3-wj28 Open WebUI: Any authenticated user can inject chats into another user's folder via chat completions | Medium | Also affects open-webui |
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