CVE-2026-45387 — open-webui
MEDIUMCVE-2026-45387 is a medium-severity (CVSS 4.3) Information Exposure vulnerability in open-webui. A fix is available for open-webui — see the affected versions and patch details below.
Open WebUI: Sharing models for others to use (read permission) also exposes model details (system prompt leakage)
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-45387.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
open-webuiReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
Description
Summary
When setting model permissions so that a group has read access to it, intending for other users to use it, those users also can read the model's system prompt.
However users may consider their system prompt confidential, so we consider this a security issue.
Compare https://genai.owasp.org/llmrisk/llm072025-system-prompt-leakage/ or prompt injections to get popular chatbots on the internet to reveal their prompt.
Details
We discovered that users can open the workspace model edit page /workspace/models/edit?id=notmymodel for models that do not appear in their workspace.
Saving is not possible, that permission check is correct.
On the API level:
/api/v1/models/model?id=notmymodel-> returns the model details, most importantly params.system- even though
/api/v1/models/listdoes NOT contain the model since it checks for write permission. /api/modelscontains the model correctly and does not reveal the system prompt.
It seems inconsistent that the REST API list does not contain an item, but if you know the id, you can access it anyway.
PoC
- create model
- give read permission to group with another user
- other user can access
/api/v1/models/model?id=notmymodel
Impact
System prommpt leakage
If this is intended behavior for the "read" permission, maybe there should be an additional "use" permission (which would be 99% of use cases of the read permission i believe).
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | open-webui | all versions | 0.9.5pip install --upgrade 'open-webui==0.9.5' |
Affected Products
open webuiopenwebuiDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for open-webui, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update open-webui to 0.9.5 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-45387 is resolved across your whole dependency graph.
Workarounds
Assume what was exposed is already known: rotate any credential, token or key that the affected component could return, restrict the endpoint to callers that genuinely need it, and strip sensitive fields from responses and error output at the boundary rather than relying on the client not to read them.
Frequently Asked Questions
Is CVE-2026-45387 in your dependencies?
Find it across PyPI, including transitive dependencies.