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CVE-2026-45349

Open WebUI: Broken Access Control for Completions API

7.1 HighFix available

Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.9.0, a user just needs to use the API endpoint: /api/chat/completions with their own API key (generated in OWUI) and the Chat ID of another user to continue the conversation of the other user. This vulnerability is fixed in 0.9.0.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
Low
User interaction
None

What an attacker can affect

Confidentiality
High
Integrity
Low
Availability
None

Exploit likelihood

0.23%Up 0.2 points since May 16, 2026
90%50%10%1%

What each source reports

CVE List Score used 7.1

Open WebUI: Broken Access Control for Completions API

Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.9.0, a user just needs to use the API endpoint: /api/chat/completions with their own API key (generated in OWUI) and the Chat ID of another user to continue the conversation of the other user. This vulnerability is fixed in 0.9.0.

Record
CVE-2026-45349
CVSS 3.1
7.1 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N
Weakness
CWE-639
Updated
2026-11-02
EUVDEUVD-2026-30605 7.1

Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.9.0, a user just needs to use the API endpoint: /api/chat/completions with their own API key (generated in OWUI) and the Chat ID of another user to continue the conversation of the other user. This vulnerability is fixed in 0.9.0.

Record
EUVD-2026-30605
CVSS 3.1
7.1 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N
Updated
2026-11-02
GitHub AdvisoriesGHSA-gfm2-xm6c-37qc 7.1

Open WebUI has Broken Access Control for Completions API

Summary

Any user X can continue the conversation of any other user Y, as long as the Chat ID of Y is known. User X does not even need to be an admin to do so.

Details

A user just needs to use the API endpoint: /api/chat/completions with their own API key (generated in OWUI) and the Chat ID of another user. OWUI does not check to match the Chat ID with the user that created that Chat ID. Note that both users will need access to the same model. This is especially relevant if there is a shared pipeline model between users.

PoC

  1. Using OWUI v0.6.18
  2. Sign in with any user X
  3. Generate an API Key for user X using the settings
  4. Create another user Y, and have a conversation in OWUI. Copy the Chat ID from the URL.
  5. User X can now use the API /api/chat/completions and the Chat ID from step 4 to continue the conversation of user Y

Impact

Large impact to any user in OWUI. People can read your conversations, and access private information if they know your Chat ID (which is in the URL of the chat).

Resolution

Fixed in commit cf4218e68, first released in v0.9.0 (Apr 2026). The chat_completion handler at backend/open_webui/main.py:1868 now explicitly verifies chat ownership via Chats.is_chat_owner(chat_id, user.id) for any request that targets an existing chat, and raises 404 for non-owners (admin bypass preserved per the documented threat model). New chats (no chat_id supplied, or freshly inserted via the is_new_chat branch) are unaffected. Users on >= 0.9.0 are not affected.

Record
GHSA-gfm2-xm6c-37qc
CVSS 3.1
7.1 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N
Weakness
CWE-639
Updated
2026-11-02
NVD 7.1

Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.9.0, a user just needs to use the API endpoint: /api/chat/completions with their own API key (generated in OWUI) and the Chat ID of another user to continue the conversation of the other user. This vulnerability is fixed in 0.9.0.

Record
CVE-2026-45349
CVSS 3.1
7.1 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N
Weakness
CWE-639
Updated
2026-11-02
OSV 7.1

Open WebUI: Broken Access Control for Completions API

Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.9.0, a user just needs to use the API endpoint: /api/chat/completions with their own API key (generated in OWUI) and the Chat ID of another user to continue the conversation of the other user. This vulnerability is fixed in 0.9.0.

Record
CVE-2026-45349
CVSS 3.1
7.1 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N
Weakness
CWE-639
Updated
2026-11-02
OSVGHSA-gfm2-xm6c-37qc 7.1

Open WebUI has Broken Access Control for Completions API

Summary

Any user X can continue the conversation of any other user Y, as long as the Chat ID of Y is known. User X does not even need to be an admin to do so.

Details

A user just needs to use the API endpoint: /api/chat/completions with their own API key (generated in OWUI) and the Chat ID of another user. OWUI does not check to match the Chat ID with the user that created that Chat ID. Note that both users will need access to the same model. This is especially relevant if there is a shared pipeline model between users.

PoC

  1. Using OWUI v0.6.18
  2. Sign in with any user X
  3. Generate an API Key for user X using the settings
  4. Create another user Y, and have a conversation in OWUI. Copy the Chat ID from the URL.
  5. User X can now use the API /api/chat/completions and the Chat ID from step 4 to continue the conversation of user Y

Impact

Large impact to any user in OWUI. People can read your conversations, and access private information if they know your Chat ID (which is in the URL of the chat).

Resolution

Fixed in commit cf4218e68, first released in v0.9.0 (Apr 2026). The chat_completion handler at backend/open_webui/main.py:1868 now explicitly verifies chat ownership via Chats.is_chat_owner(chat_id, user.id) for any request that targets an existing chat, and raises 404 for non-owners (admin bypass preserved per the documented threat model). New chats (no chat_id supplied, or freshly inserted via the is_new_chat branch) are unaffected. Users on >= 0.9.0 are not affected.

Record
GHSA-gfm2-xm6c-37qc
CVSS 3.1
7.1 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N
Weakness
CWE-639
Updated
2026-11-02
OSVPYSEC-2026-2726 7.1

Open WebUI has Broken Access Control for Completions API

Summary

Any user X can continue the conversation of any other user Y, as long as the Chat ID of Y is known. User X does not even need to be an admin to do so.

Details

A user just needs to use the API endpoint: /api/chat/completions with their own API key (generated in OWUI) and the Chat ID of another user. OWUI does not check to match the Chat ID with the user that created that Chat ID. Note that both users will need access to the same model. This is especially relevant if there is a shared pipeline model between users.

PoC

  1. Using OWUI v0.6.18
  2. Sign in with any user X
  3. Generate an API Key for user X using the settings
  4. Create another user Y, and have a conversation in OWUI. Copy the Chat ID from the URL.
  5. User X can now use the API /api/chat/completions and the Chat ID from step 4 to continue the conversation of user Y

Impact

Large impact to any user in OWUI. People can read your conversations, and access private information if they know your Chat ID (which is in the URL of the chat).

Resolution

Fixed in commit cf4218e68, first released in v0.9.0 (Apr 2026). The chat_completion handler at backend/open_webui/main.py:1868 now explicitly verifies chat ownership via Chats.is_chat_owner(chat_id, user.id) for any request that targets an existing chat, and raises 404 for non-owners (admin bypass preserved per the documented threat model). New chats (no chat_id supplied, or freshly inserted via the is_new_chat branch) are unaffected. Users on >= 0.9.0 are not affected.

Record
PYSEC-2026-2726
CVSS 3.1
7.1 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
open-webui
PyPI
 through 0.8.12
0.9.0
open-webui
PyPI
 before 0.9.0, plus listed versions
0.1.1240.1.1250.2.00.2.10.2.2
Show 45 moreShow less
0.2.30.2.40.2.50.3.00.3.10.3.100.3.120.3.130.3.140.3.150.3.160.3.170.3.17.dev20.3.17.dev30.3.17.dev40.3.17.dev50.3.180.3.190.3.20.3.200.3.210.3.220.3.230.3.240.3.250.3.260.3.270.3.27.dev10.3.27.dev20.3.27.dev30.3.280.3.290.3.30.3.300.3.30.dev10.3.30.dev20.3.310.3.31.dev10.3.320.3.330.3.33.dev10.3.340.3.350.3.40.3.5
0.9.0

History

History
RecordedChangedSources
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-45349 is a high vulnerability (CVSS 7.1) in Openwebui Open Webui, published May 14, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.23%, the 14th percentile. Fixed in open-webui 0.9.0.

References

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Left out here: 101 versions. The JSON record has them.

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