CVE-2026-44557

Global Knowledge Base Enumeration via knowledge-bases Meta-Collection

Affected Component

Retrieval collection access validation:

• backend/open_webui/routers/retrieval.py (lines 2330-2355, _validate_collection_access)
• backend/open_webui/routers/retrieval.py (query endpoints, e.g. POST /query/doc)

Affected Versions

Current main branch (commit 6fdd19bf1) and likely all versions with the knowledge base subsystem.

Description

The _validate_collection_access function uses an incomplete allowlist that only enforces ownership checks for collections matching user-memory-* and file-* patterns. All other collection names pass through unchecked, including the system-level knowledge-bases meta-collection, which stores the IDs, names, and descriptions of every knowledge base on the instance.

Any authenticated user can query this meta-collection directly via the retrieval query endpoints to obtain a global index of all knowledge bases across all users.

# retrieval.py:2330-2355, incomplete collection allowlist
def _validate_collection_access(user, collection_name, ...):
    if collection_name.startswith('user-memory-'):
        # Check user-memory ownership
        ...
    elif collection_name.startswith('file-'):
        # Check file access
        ...
    # Everything else (including "knowledge-bases") passes through unchecked

This finding is the enabler for the KB destruction (process/web), KB content injection (process/file), and RAG vector search access bypass findings, all of which require knowing a target KB's UUID. Without this enumeration, UUIDs are random and practically unguessable; with it, UUIDs across the entire instance are trivially obtained.

CVSS 3.1 Breakdown

Attack Scenario

1. Attacker (any authenticated user) sends:

   POST /api/v1/retrieval/query/doc
   {
     "collection_name": "knowledge-bases",
     "query": "confidential"
   }
   

2. _validate_collection_access does not recognize the knowledge-bases prefix and lets the request pass.
3. The vector search returns the most relevant documents from the meta-collection, knowledge base records including their UUIDs, names, and descriptions, across all users on the instance.
4. Attacker varies the query to enumerate more KBs: "project", "internal", "private", etc.
5. Attacker now has a full target list for subsequent attacks (destruction, poisoning, content extraction).

Preconditions

• Attacker must have a valid user account

• Information disclosure: KB names and descriptions may reveal sensitive project names, internal initiatives, or user activities
• Enabler for other attacks: Unlocks the following findings by supplying the required target UUIDs:
  • KB destruction/poisoning via process/web
  • Cross-user content injection via process/file
  • RAG vector search access bypass in retrieval/utils.py
• Transforms these from theoretical (requires UUID guessing) to trivially exploitable (UUIDs enumerable)

The application does not perform an authorization check before performing a sensitive operation. Typical impact: unauthorized access to restricted functionality or data.

CVE-2026-44557 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 (0.9.0); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2026-44557? CVE-2026-44557 is a medium-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.
2. How severe is CVE-2026-44557? CVE-2026-44557 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.
3. Which versions of open-webui are affected by CVE-2026-44557? open-webui (pip) versions <= 0.8.12 is affected.
4. Is there a fix for CVE-2026-44557? Yes. CVE-2026-44557 is fixed in 0.9.0. Upgrade to this version or later.
5. Is CVE-2026-44557 exploitable, and should I be worried? Whether CVE-2026-44557 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
6. What actually determines whether CVE-2026-44557 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.
7. How do I fix CVE-2026-44557? Upgrade open-webui to 0.9.0 or later.