CVE-2026-70484

Open WebUI is an extensible, feature-rich, and user-friendly self-hosted AI platform. From 0.7.0 until 0.11.0, the legacy chat-completions features block trusted a client-supplied image_generation flag and did not re-check the features.image_generation permission that the direct image routes and native function-calling path enforce. An authenticated user whose image-generation permission had been revoked could still consume the operator's configured image provider through chat completions, spending API credits and provider quota and writing generated files to operator storage, without exposing provider credentials or other users' data. This issue is fixed in 0.11.0.

Open WebUI is an extensible, feature-rich, and user-friendly self-hosted AI platform. From 0.7.0 until 0.11.0, the legacy chat-completions features block trusted a client-supplied image_generation flag and did not re-check the features.image_generation permission that the direct image routes and native function-calling path enforce. An authenticated user whose image-generation permission had been revoked could still consume the operator's configured image provider through chat completions, spending API credits and provider quota and writing generated files to operator storage, without exposing provider credentials or other users' data. This issue is fixed in 0.11.0.

Summary

An authenticated user whose features.image_generation permission has been revoked can still make the server generate images by sending the feature flag in a chat-completion request. The chat pipeline took the client-supplied features object at face value and never re-checked the permission that the direct image routes enforce, so the denial applied to the UI affordance but not to the server-side generation path.

Preconditions

Image generation must be enabled and a provider configured by the administrator (ENABLE_IMAGE_GENERATION is off by default). The per-user permission defaults to granted, so only deployments where an administrator explicitly revoked it for some users are affected. On 0.10.0 and later the caller must also set params.function_calling to legacy; on 0.9.x and earlier the legacy mode was the default, so no special parameter was needed. Deployments on native function calling are unaffected, since that path checks the permission before registering the image tools.

Impact

A user the administrator has explicitly denied image generation can consume the operator's configured provider through the chat API, spending the operator's API credits and provider quota and writing generated files to the operator's storage. Where an image is present in the conversation and image editing is enabled, the same handler reaches the image-edit provider as well. No provider credentials are exposed, and no other user's data is reachable.

Fix

Fixed in 897d69a (#26703). The legacy chat-features block now re-checks features.image_generation against the caller's permissions before invoking the image handler, matching the check the direct image routes and the native function-calling path already performed.

Root cause

The chat-completions endpoint stored the request's features object into request metadata, and process_chat_payload in the chat middleware dispatched to the image handler purely on the truthiness of that client-supplied flag. Permission enforcement lived on the two surfaces that were reached from the UI, the direct /images/generations and /images/edit routes and the native function-calling tool registration, and was simply absent on the legacy chat path. The flag was treated as a statement of user intent, which it is, rather than as an authorization decision, which the handler behind it made it.

Credits

@DavidCarliez, for identifying that the chat pipeline honours the client-supplied image-generation feature flag without re-checking the permission.

Open WebUI is an extensible, feature-rich, and user-friendly self-hosted AI platform. From 0.7.0 until 0.11.0, the legacy chat-completions features block trusted a client-supplied image_generation flag and did not re-check the features.image_generation permission that the direct image routes and native function-calling path enforce. An authenticated user whose image-generation permission had been revoked could still consume the operator's configured image provider through chat completions, spending API credits and provider quota and writing generated files to operator storage, without exposing provider credentials or other users' data. This issue is fixed in 0.11.0.

Open WebUI is an extensible, feature-rich, and user-friendly self-hosted AI platform. From 0.7.0 until 0.11.0, the legacy chat-completions features block trusted a client-supplied image_generation flag and did not re-check the features.image_generation permission that the direct image routes and native function-calling path enforce. An authenticated user whose image-generation permission had been revoked could still consume the operator's configured image provider through chat completions, spending API credits and provider quota and writing generated files to operator storage, without exposing provider credentials or other users' data. This issue is fixed in 0.11.0.

Summary

An authenticated user whose features.image_generation permission has been revoked can still make the server generate images by sending the feature flag in a chat-completion request. The chat pipeline took the client-supplied features object at face value and never re-checked the permission that the direct image routes enforce, so the denial applied to the UI affordance but not to the server-side generation path.

Preconditions

Image generation must be enabled and a provider configured by the administrator (ENABLE_IMAGE_GENERATION is off by default). The per-user permission defaults to granted, so only deployments where an administrator explicitly revoked it for some users are affected. On 0.10.0 and later the caller must also set params.function_calling to legacy; on 0.9.x and earlier the legacy mode was the default, so no special parameter was needed. Deployments on native function calling are unaffected, since that path checks the permission before registering the image tools.

Impact

A user the administrator has explicitly denied image generation can consume the operator's configured provider through the chat API, spending the operator's API credits and provider quota and writing generated files to the operator's storage. Where an image is present in the conversation and image editing is enabled, the same handler reaches the image-edit provider as well. No provider credentials are exposed, and no other user's data is reachable.

Fix

Fixed in 897d69a (#26703). The legacy chat-features block now re-checks features.image_generation against the caller's permissions before invoking the image handler, matching the check the direct image routes and the native function-calling path already performed.

Root cause

The chat-completions endpoint stored the request's features object into request metadata, and process_chat_payload in the chat middleware dispatched to the image handler purely on the truthiness of that client-supplied flag. Permission enforcement lived on the two surfaces that were reached from the UI, the direct /images/generations and /images/edit routes and the native function-calling tool registration, and was simply absent on the legacy chat path. The flag was treated as a statement of user intent, which it is, rather than as an authorization decision, which the handler behind it made it.

Credits

@DavidCarliez, for identifying that the chat pipeline honours the client-supplied image-generation feature flag without re-checking the permission.

Summary

An authenticated user whose features.image_generation permission has been revoked can still make the server generate images by sending the feature flag in a chat-completion request. The chat pipeline took the client-supplied features object at face value and never re-checked the permission that the direct image routes enforce, so the denial applied to the UI affordance but not to the server-side generation path.

Preconditions

Image generation must be enabled and a provider configured by the administrator (ENABLE_IMAGE_GENERATION is off by default). The per-user permission defaults to granted, so only deployments where an administrator explicitly revoked it for some users are affected. On 0.10.0 and later the caller must also set params.function_calling to legacy; on 0.9.x and earlier the legacy mode was the default, so no special parameter was needed. Deployments on native function calling are unaffected, since that path checks the permission before registering the image tools.

Impact

A user the administrator has explicitly denied image generation can consume the operator's configured provider through the chat API, spending the operator's API credits and provider quota and writing generated files to the operator's storage. Where an image is present in the conversation and image editing is enabled, the same handler reaches the image-edit provider as well. No provider credentials are exposed, and no other user's data is reachable.

Fix

Fixed in 897d69a (#26703). The legacy chat-features block now re-checks features.image_generation against the caller's permissions before invoking the image handler, matching the check the direct image routes and the native function-calling path already performed.

Root cause

The chat-completions endpoint stored the request's features object into request metadata, and process_chat_payload in the chat middleware dispatched to the image handler purely on the truthiness of that client-supplied flag. Permission enforcement lived on the two surfaces that were reached from the UI, the direct /images/generations and /images/edit routes and the native function-calling tool registration, and was simply absent on the legacy chat path. The flag was treated as a statement of user intent, which it is, rather than as an authorization decision, which the handler behind it made it.

Credits

@DavidCarliez, for identifying that the chat pipeline honours the client-supplied image-generation feature flag without re-checking the permission.