CVE-2026-45387

mediumpriority · track · 0EPSS 0.002 · 12 %ileEURUUS
grimoire priorityP3 · Track
Exploitable?
—
no known exploitation
Likely / severe?
0.22% (12th) EPSS
CVSS 4.3 · medium
Is it mine?
4 products
Check your exposure
Who says so?
5 sources
cnnvd · enisa_euvd · fstec_bdu · osv

EPSS · scored 2026-10-27

Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.9.5, 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 this is considered a security issue. This vulnerability is fixed in 0.9.5.

01

cvss

Technical severity, 0–10. One row per scoring source.

4.3
010

base score 0–10 · higher = more severe · hover a vector to decode

v3.14.3mediumAV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:Nsecondary · FSTEC (BDU) RU
v3.14.3mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:Nsecondary · ENISA EU
v3.14.3mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:Nsecondary · security-advisories@github.comexploitability 2.8 · impact 1.4
v3.14.3mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:Nsecondary · OSV
v3.14mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N/E:Usecondary · CVSS-BT (t0sche)
02

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Exploitation: poc · Automatable: no · Technical Impact: partialcoordinatorcisa_ssvcUS
03

weaknesses

The CWE weakness classes this flaw belongs to.

04

affected products (4)

Products and version ranges known to be affected.

05

advisories (2)

Vendor and ecosystem advisories describing this.

  • GHSA-h2cw-7qw9-56xrOpen WebUI: Sharing models for others to use (read permission) also exposes model details (system prompt leakage)2026-05-14ghsa · osvUS

    ### 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/list``` does NOT contain the model since it checks for write permission. - ```/api/models``` contains 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).

  • PYSEC-2026-2728Open WebUI: Sharing models for others to use (read permission) also exposes model details (system prompt leakage)2026-07-13vendor · osvUS

    ### 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/list``` does NOT contain the model since it checks for write permission. - ```/api/models``` contains 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).

06

also known as (7)

Other names and identifiers for this entity.

07

sources

Which sources assert this record, and when.

published 2026-05-15modified 2026-06-17
08

references (4)

External citations — patches, advisories, analysis.

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