PYSEC-2026-2695

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Import Source
https://github.com/pypa/advisory-database/blob/main/vulns/open-webui/PYSEC-2026-2695.yaml
JSON Data
https://api.osv.dev/v1/vulns/PYSEC-2026-2695
Aliases
Published
2026-07-13T15:46:19Z
Modified
2026-07-13T16:31:52Z
Severity
  • 7.1 (High) CVSS_V4 - CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N CVSS Calculator
Summary
Open WebUI: Cross-origin postMessage confirmation bypass via action:submit
Details

Summary

The chat message listener allows non-same-origin input:prompt and action:submit messages, so an external site can set prompt text and trigger submitPrompt() in an authenticated victim session. I validated this with a cross-origin attacker page that auto-posted messages and caused unauthorized POST /api/v1/chats/new and POST /api/chat/completions requests containing attacker-controlled prompts. This enables cross-site forced actions and model/tool execution under victim privileges without consent.

Details

The chat page's window message listener in src/lib/components/chat/Chat.svelte processes message types including input:prompt and action:submit without adequately enforcing same-origin restrictions. Based on code around lines ~597-616, input text is set directly from event.data.text; action:submit proceeds to submitPrompt() on the current prompt. The logic does not apply a strict origin allowlist and permits non-same-origin control of the chat input and submission flow, leading to cross-origin command execution in the victim's authenticated UI context. As a result, backend API calls (e.g., POST /api/v1/chats/new, POST /api/chat/completions) are sent under victim credentials.

Normally, via the input:prompt:submit postMessage type, this results in a "Confirm Prompt from Embed" confirmation dialog:

https://github.com/open-webui/open-webui/blob/9bd84258d09eefe7bf975878fb0e31a5dadfe0f8/src/lib/components/chat/Chat.svelte#L604-L622

However, combining the two other types, it is possible to achieve the same effect without this confirmation:

https://github.com/open-webui/open-webui/blob/9bd84258d09eefe7bf975878fb0e31a5dadfe0f8/src/lib/components/chat/Chat.svelte#L584-L602

PoC

  1. Set up a local Open WebUI instance and log in to it, making sure a model is configured
  2. Host the following HTML anywhere and visit it (optionally change http://127.0.0.1:14000 to your instance Base URL):
<h1>Click anywhere</h1>
<script>
  function sleep(ms) {
    return new Promise(r => setTimeout(r, ms));
  }
  
  onclick = async () => {
    w = window.open('http://127.0.0.1:14000');
    await sleep(2000);
    w.postMessage({ type: 'input:prompt', text: "INJECTED PROMPT" }, '*');
    await sleep(500);
    w.postMessage({ type: 'action:submit' }, '*');
  }
</script>
  1. Click anywhere on the page, then notice without further interaction the "INJECTED PROMPT" is executed on the Open WebUI instance
image

Impact

Conditions required: The victim must be authenticated to Open WebUI in the browser (token cookie present).

This issue enables cross-site forced actions under the victim's identity. An attacker can silently inject prompts and trigger model/tool execution (e.g., code interpreter, web search, retrieval, terminal/tool servers) as the victim without confirmation.

Original Agent Report

References

Affected packages

PyPI / open-webui

Package

Name
open-webui
View open source insights on deps.dev
Purl
pkg:pypi/open-webui

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected
Fixed
0.9.6

Affected versions

0.*
0.1.124
0.1.125
0.2.0
0.2.1
0.2.2
0.2.3
0.2.4
0.2.5
0.3.0
0.3.1
0.3.2
0.3.3
0.3.4
0.3.5
0.3.6
0.3.7
0.3.8
0.3.9
0.3.10
0.3.12
0.3.13
0.3.14
0.3.15
0.3.16
0.3.17.dev2
0.3.17.dev3
0.3.17.dev4
0.3.17.dev5
0.3.17
0.3.18
0.3.19
0.3.20
0.3.21
0.3.22
0.3.23
0.3.24
0.3.25
0.3.26
0.3.27.dev1
0.3.27.dev2
0.3.27.dev3
0.3.27
0.3.28
0.3.29
0.3.30.dev1
0.3.30.dev2
0.3.30
0.3.31.dev1
0.3.31
0.3.32
0.3.33.dev1
0.3.33
0.3.34
0.3.35
0.4.0.dev1
0.4.0.dev2
0.4.0
0.4.1
0.4.2
0.4.3
0.4.4
0.4.5
0.4.6.dev1
0.4.6
0.4.7
0.4.8
0.5.0.dev1
0.5.0.dev2
0.5.0
0.5.1
0.5.2
0.5.3.dev1
0.5.3
0.5.4
0.5.5
0.5.6
0.5.7
0.5.8
0.5.9
0.5.10
0.5.11
0.5.12
0.5.13
0.5.14
0.5.15
0.5.16
0.5.17
0.5.18
0.5.19
0.5.20
0.6.0
0.6.1
0.6.2
0.6.3
0.6.4
0.6.5
0.6.6.dev1
0.6.6
0.6.7
0.6.8
0.6.9
0.6.10
0.6.11
0.6.12
0.6.13
0.6.14
0.6.15
0.6.16
0.6.18
0.6.19
0.6.20
0.6.21
0.6.22
0.6.23
0.6.24
0.6.25
0.6.26.dev1
0.6.26
0.6.27
0.6.28
0.6.29
0.6.30
0.6.31
0.6.32
0.6.33
0.6.34
0.6.35
0.6.36
0.6.37
0.6.38
0.6.39
0.6.40
0.6.41
0.6.42
0.6.43
0.7.0
0.7.1
0.7.2
0.8.0
0.8.1
0.8.2
0.8.3
0.8.4
0.8.5
0.8.6
0.8.7
0.8.8
0.8.9
0.8.10
0.8.11
0.8.12
0.9.0
0.9.1
0.9.2
0.9.3
0.9.4
0.9.5

Database specific

source 
"https://github.com/pypa/advisory-database/blob/main/vulns/open-webui/PYSEC-2026-2695.yaml"