Summary
Open WebUI: Deletion of directories and file embeddings in other knowledge bases via sync cleanup
A user with write access to one knowledge base could delete directories, and drop file embeddings, belonging to knowledge bases they do not control. The sync cleanup endpoint verified write access on the knowledge base named in the URL and then acted on the directory and file ids supplied in the request body without checking that those objects belonged to that knowledge base.
Preconditions
Default configuration, no flags involved. The attacker needs write access to at least one knowledge base, which comes from owning one, from a write access grant, or from the admin role; workspace.knowledge is off by default, so an ordinary user cannot simply create one. They also need the victim's directory or file id, which are UUIDs and are not enumerable, so in practice the attacker is someone who can already see the target knowledge base, typically a read-only collaborator on a shared one. Deployments where no knowledge base is shared beyond its owner are not reachable.
Root cause
Affected component: backend/open_webui/routers/knowledge.py, handler sync_knowledge_cleanup, endpoint POST /api/v1/knowledge/{id}/sync/cleanup. Affected setup: all builds from 0.9.6 onward, no optional dependency involved.
The handler treated the write-access check on the URL knowledge base as authorization for everything it went on to do, but the objects it acted on came from the request body and were addressed by primary key alone. Directory deletion at the model layer deletes by directory id and has no notion of a parent knowledge base, so the only thing that could have bound the two together was a membership check in the handler, and there was none. The explicit directory-delete endpoint in the same router already carried that check, which is what makes this a gap in one handler rather than a missing model-layer control.
Credits
Reported by @whyiug.
Impact
The attacker deletes a target directory and, because the deletion runs without moving files to the parent, the knowledge_file associations for every file in that subtree are removed as well, so those documents silently drop out of the victim's knowledge base and out of its retrieval results. Separately, the per-file vector cleanup dropped the standalone file-<id> collection for any file id, breaking chat-with-file for that document. The stored files and their database rows survive, since that path was gated on file ownership, and an owner can restore the state by re-adding and reprocessing. Nothing about the target knowledge base's contents is disclosed to the attacker.
The application does not correctly enforce access controls, allowing a principal to access resources or operations beyond their granted permissions. Typical impact: unauthorized data access or execution of privileged operations.
CVE-2026-70488 has a CVSS score of 4.3 (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 (0.11.0); 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.
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Fixed in https://github.com/open-webui/open-webui/pull/26722. Both request-body loops are now scoped to the knowledge base in the URL: a directory is resolved and skipped unless its knowledge_id matches, and the per-file vector cleanup runs only for files that are members of that knowledge base. Upgrading fully resolves the issue.
Frequently Asked Questions
- What is CVE-2026-70488? CVE-2026-70488 is a medium-severity incorrect authorization vulnerability in open-webui (pip), affecting versions >= 0.9.6, <= 0.10.2. It is fixed in 0.11.0. The application does not correctly enforce access controls, allowing a principal to access resources or operations beyond their granted permissions.
- How severe is CVE-2026-70488? CVE-2026-70488 has a CVSS score of 4.3 (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-2026-70488? open-webui (pip) versions >= 0.9.6, <= 0.10.2 is affected.
- Is there a fix for CVE-2026-70488? Yes. CVE-2026-70488 is fixed in 0.11.0. Upgrade to this version or later.
- Is CVE-2026-70488 exploitable, and should I be worried? Whether CVE-2026-70488 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-2026-70488 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-2026-70488? Upgrade
open-webuito 0.11.0 or later.