CVE-2026-45351: Open webui Open WebUI Exposes System Prompt Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-jh9g-8jqw-m2qx",
  "modified" : "2026-05-19T15:59:58Z",
  "published" : "2026-05-14T20:25:04Z",
  "aliases" : [ "CVE-2026-45351" ],
  "summary" : "Open WebUI Exposes System Prompt to Regular User [Non-Admin]",
  "details" : "### Summary\n_A regular user [non-admin] can view the system prompt of the model which is set by an admin._\n\n### Details\n_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_\n\n### Affected System\n_Open WebUI v0.6.40 \"main\" branch_\n\n### Vulnerability Details and Advisory from OWASP\nLLM07:2025 System Prompt Leakage - https://genai.owasp.org/llmrisk/llm072025-system-prompt-leakage/\n\n\n### PoC\n_1. Regular User [Non-Admin] login on Open WebUI application._\n_2. A series of web requests get generated by the application, and the http://IP:8080/api/models? is also gets generated by application ._\n_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._\n<img width=\"940\" height=\"352\" alt=\"system prompt leak\" src=\"https://github.com/user-attachments/assets/bd2c76f1-398f-4bc8-a8b2-5e14a768c560\" />\n\n### Web Request\nGET /api/models? HTTP/1.1\nHost: localhost:8080\nsec-ch-ua-platform: \"Linux\"\nauthorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpZCI6IjdmYjUxMmFhLTBmMTAtNDRkZi1iOWY1LThmNDg2MWFhNWFmOCIsImV4cCI6MTc2NjU2MjE5OH0.yJpavBynKItPQv76SMGKK012JIf29PVUv9sjuCDuRGQ\nAccept-Language: en-US,en;q=0.9\nsec-ch-ua: \"Chromium\";v=\"141\", \"Not?A_Brand\";v=\"8\"\nsec-ch-ua-mobile: ?0\nUser-Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/141.0.0.0 Safari/537.36\nAccept: application/json\nContent-Type: application/json\nSec-Fetch-Site: same-origin\nSec-Fetch-Mode: cors\nSec-Fetch-Dest: empty\nReferer: http://localhost:8080/\nAccept-Encoding: gzip, deflate, br\nCookie: token=eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpZCI6IjdmYjUxMmFhLTBmMTAtNDRkZi1iOWY1LThmNDg2MWFhNWFmOCIsImV4cCI6MTc2NjU2MjE5OH0.yJpavBynKItPQv76SMGKK012JIf29PVUv9sjuCDuRGQ\nConnection: keep-alive\n\n\n### Impact\n_1. System prompts can reveal the model instructions, providing an attackers with inside knowledge about the system capabilities and bypass restrictions._\n_2. Attacker can perform content manipulation affecting the input/output of the model._\n\n### Details from MITRE ATLAS\nDiscover LLM System Information - https://atlas.mitre.org/techniques/AML.T0069\nDiscover LLM System Information: System Instruction Keywords - https://atlas.mitre.org/techniques/AML.T0069.001\nDiscover LLM System Information: System Prompt - https://atlas.mitre.org/techniques/AML.T0069.002\n\n\n### Recommendation\n_1. The web response should not reveal system prompt and related internal/back-end details regarding the model to the regular user._\n_2. Only the model name and non-sensitive details should be revealed to regular user and internal/back-end details should not be disclosed._",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "open-webui"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.8.9"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 0.8.8"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/open-webui/open-webui/security/advisories/GHSA-jh9g-8jqw-m2qx"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-45351"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/open-webui/open-webui"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/open-webui/open-webui/releases/tag/v0.8.9"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-200" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-05-14T20:25:04Z",
    "nvd_published_at" : "2026-05-15T22:16:55Z"
  }
}