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.
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
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
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.
CVE-2026-45351 has a CVSS score of 6.5 (Medium). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (0.8.9); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Remediation advice
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.
Frequently Asked Questions
- What is CVE-2026-45351? CVE-2026-45351 is a medium-severity security vulnerability in open-webui (pip), affecting versions <= 0.8.8. It is fixed in 0.8.9.
- How severe is CVE-2026-45351? CVE-2026-45351 has a CVSS score of 6.5 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of open-webui are affected by CVE-2026-45351? open-webui (pip) versions <= 0.8.8 is affected.
- Is there a fix for CVE-2026-45351? Yes. CVE-2026-45351 is fixed in 0.8.9. Upgrade to this version or later.
- Is CVE-2026-45351 exploitable, and should I be worried? Whether CVE-2026-45351 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-45351 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-45351? Upgrade
open-webuito 0.8.9 or later.