Summary
Open WebUI: Low-privilege authenticated users can enumerate and stop global background tasks, causing system-wide chat disruption
Impact
Type of vulnerability:
broken object-level authorization affecting a global runtime control-plane endpoint.
Who is impacted:
- all users in a multi-user Open WebUI deployment
- any user currently running a background task, especially chat generation tasks
- administrators indirectly, because normal users can disrupt system-wide usage without admin privileges
Direct impact:
- cross-user task ID disclosure
- cross-user task cancellation
Practical impact:
- interruption of long-running chat responses
- interruption of background indexing or ingestion tasks associated with shared runtime jobs
- one ordinary authenticated low-privilege user can continuously poll
/api/tasksand immediately cancel every newly created active task - with a simple loop or script, this becomes a practical persistent denial-of-service against chat usage for all users on the instance
- in a multi-user deployment, normal users may be unable to complete any chat generation while the attacker continues polling and cancelling tasks
Why severity is meaningful:
- privileges required: low, only an authenticated non-admin account
- scope: cross-user
- impact class: integrity and availability
- exploitation complexity: low once logged in
This is not full account takeover or privilege escalation, but it enables platform-wide operational disruption from a low-privilege account. In practice, sustained exploitation can make chat functionality effectively unusable for other users on the system.
The application does not perform an authorization check before performing a sensitive operation. Typical impact: unauthorized access to restricted functionality or data.
CVE-2026-45399 has a CVSS score of 7.1 (High). 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 (0.9.0); 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
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
Frequently Asked Questions
- What is CVE-2026-45399? CVE-2026-45399 is a high-severity missing authorization vulnerability in open-webui (pip), affecting versions <= 0.8.12. It is fixed in 0.9.0. The application does not perform an authorization check before performing a sensitive operation.
- How severe is CVE-2026-45399? CVE-2026-45399 has a CVSS score of 7.1 (High). 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-2026-45399? open-webui (pip) versions <= 0.8.12 is affected.
- Is there a fix for CVE-2026-45399? Yes. CVE-2026-45399 is fixed in 0.9.0. Upgrade to this version or later.
- Is CVE-2026-45399 exploitable, and should I be worried? Whether CVE-2026-45399 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-2026-45399 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-2026-45399? Upgrade
open-webuito 0.9.0 or later.