{"description":"Trending threats, MITRE ATT\u0026CK coverage, and detection metadata. Fed continuously.","feed_url":"https://feed.craftedsignal.io/tags/cve-2026-45399/feed.json","home_page_url":"https://feed.craftedsignal.io/","items":[{"_cs_actors":[],"_cs_cpes":["cpe:2.3:a:openwebui:open_webui:0.6.41:*:*:*:*:*:*:*"],"_cs_cves":[{"cvss":4.3,"id":"CVE-2025-63681"}],"_cs_exploited":false,"_cs_has_poc":false,"_cs_poc_references":[],"_cs_products":["open-webui (\u003c= 0.8.12)"],"_cs_severities":["medium"],"_cs_tags":["authorization","denial-of-service","cve-2026-45399"],"_cs_type":"advisory","_cs_vendors":["Open WebUI"],"content_html":"\u003cp\u003eOpen WebUI versions 0.8.12 and earlier suffer from a broken object-level authorization vulnerability that allows authenticated, low-privilege users to enumerate and stop tasks belonging to other users. This vulnerability, identified as CVE-2026-45399 and a prior disclosure as CVE-2025-63681, enables an attacker to disrupt system-wide chat usage by repeatedly canceling active tasks. The vulnerability stems from insufficient authorization checks on the \u003ccode\u003e/api/tasks\u003c/code\u003e and \u003ccode\u003e/api/tasks/stop/{task_id}\u003c/code\u003e endpoints, which operate on a global task namespace. A fix was implemented in version 0.9.0 of Open WebUI. This issue highlights the risk of relying on weak authorization schemes, where simply being an authenticated user grants access to sensitive system functions.\u003c/p\u003e\n\u003ch2 id=\"attack-chain\"\u003eAttack Chain\u003c/h2\u003e\n\u003col\u003e\n\u003cli\u003eAn attacker obtains a valid user account on the Open WebUI instance.\u003c/li\u003e\n\u003cli\u003eThe attacker authenticates to the Open WebUI instance using their credentials.\u003c/li\u003e\n\u003cli\u003eThe attacker sends a GET request to \u003ccode\u003e/api/tasks\u003c/code\u003e to enumerate all active task IDs on the system.\u003c/li\u003e\n\u003cli\u003eThe server returns a list of task IDs, including those belonging to other users.\u003c/li\u003e\n\u003cli\u003eThe attacker selects a task ID belonging to another user.\u003c/li\u003e\n\u003cli\u003eThe attacker sends a POST request to \u003ccode\u003e/api/tasks/stop/{task_id}\u003c/code\u003e, replacing \u003ccode\u003e{task_id}\u003c/code\u003e with the target task ID.\u003c/li\u003e\n\u003cli\u003eThe server, lacking proper authorization checks, attempts to stop the specified task.\u003c/li\u003e\n\u003cli\u003eThe targeted user\u0026rsquo;s task is interrupted, causing disruption to their ongoing activity.\u003c/li\u003e\n\u003c/ol\u003e\n\u003ch2 id=\"impact\"\u003eImpact\u003c/h2\u003e\n\u003cp\u003eThis vulnerability impacts all users in a multi-user Open WebUI deployment, particularly those running background tasks such as chat generation. A single low-privilege user can effectively cause a denial-of-service by continuously canceling tasks, making the chat functionality unusable for other users. This affects integrity and availability, allowing unauthorized interruption of legitimate operations.\u003c/p\u003e\n\u003ch2 id=\"recommendation\"\u003eRecommendation\u003c/h2\u003e\n\u003cul\u003e\n\u003cli\u003eUpgrade to Open WebUI version 0.9.0 or later to remediate CVE-2026-45399 and CVE-2025-63681, which addresses the broken object-level authorization.\u003c/li\u003e\n\u003cli\u003eDeploy the Sigma rule \u0026ldquo;Detect Open WebUI Task Enumeration\u0026rdquo; to identify potential exploitation attempts using the \u003ccode\u003e/api/tasks\u003c/code\u003e endpoint.\u003c/li\u003e\n\u003cli\u003eDeploy the Sigma rule \u0026ldquo;Detect Open WebUI Task Cancellation\u0026rdquo; to detect unauthorized task cancellation attempts via the \u003ccode\u003e/api/tasks/stop/{task_id}\u003c/code\u003e endpoint.\u003c/li\u003e\n\u003c/ul\u003e\n","date_modified":"2026-05-14T20:32:20Z","date_published":"2026-05-14T20:32:20Z","id":"https://feed.craftedsignal.io/briefs/2026-05-open-webui-task-kill/","summary":"Open WebUI is vulnerable to broken object-level authorization, allowing low-privilege authenticated users to enumerate and stop global background tasks across the system, leading to a denial-of-service condition and is tracked as CVE-2026-45399 and CVE-2025-63681.","title":"Open WebUI Broken Authorization Allows Task Cancellation","url":"https://feed.craftedsignal.io/briefs/2026-05-open-webui-task-kill/"}],"language":"en","title":"CraftedSignal Threat Feed — Cve-2026-45399","version":"https://jsonfeed.org/version/1.1"}