vulnerability / NVI-00015214 / Revision 2
Open WebUI: Stored XSS via unescaped KaTeX render-error fallback in rendered messages
GitHub lists this reviewed advisory for open-webui. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.
This report has not inspected your inventory, configuration, deployed build, reachability or evidence. A catalog listing and a severity score do not establish exposure or compromise.
01 / Meaning
Why it matters
Published affected context helps an owner decide what evidence to gather. This report has not examined your application.
8.7 high
GitHub source severity; exploitability and local consequence require separate evidence.
As of · GitHub Advisory Database
0.403%
FIRST EPSS model v2026.06.15; exploitation probability over 30 days, percentile 0.34722. Missing scores are unknown.
As of · FIRST EPSS
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
open-webui
source listed>= 0.10.0, < 0.11.0
## Summary Any authenticated user can store a chat message whose math block makes KaTeX fail with a stack overflow instead of a parse error. When that happens the renderer falls back to inserting the original math source into the page as HTML rather than as text, so script in the message runs in the browser of whoever views it. Every surface that renders messages is affected, including shared chats and channels, and the missing control is output escaping on the error path. ## Preconditions Default configuration, no flags involved. The attacker needs a normal user account and a way to get the target to open the content: a shared chat link, a channel the target reads, or any other message surface. No admin rights and no non-default settings are required on either side. ## Impact Script executes in the viewer's browser on the Open WebUI origin, which puts the session token in localStorage within reach and therefore allows taking over the viewing account. If the viewer is an administrator, that is administrator access to the instance. Exploitation needs the target to open the content, but nothing beyond that: no interaction with the message itself. Server-side data and availability a
03 / Response
What to do next
- investigate
Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. FIRST EPSS
A fixed release is not deployment evidence.
Check current vendor support and compatibility. After making a change, verify the deployed build and relevant runtime conditions. Keep the evidence, owner and time. An updated lockfile alone does not prove what is running.
04 / Limits
What this report cannot establish
- Customer inventory, deployment, reachability and exploitation have not been inspected.
05 / Provenance
Sources you can inspect
Each assertion retains its source. Mirrored records may repeat one underlying publisher; additional links are not independent corroboration.
- GHSA-pwxh-7358-jq2x ↗
GitHub Advisory Database · vendor advisory
Observed . GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.
- CVE-2026-70492 ↗
FIRST EPSS · official catalog
Observed . FIRST EPSS; probability of exploitation in the next 30 days, not local compromise. Dataset date/model retained; FIRST services terms apply.
Public revision history
Only published revisions appear here. Routine fetches do not create a material-change event.
- Revision 2 ·
Dated EPSS estimate updated; this is not a new disclosure or proof of exploitation.
- Revision 1 ·
First indexed by Null; source disclosure date is shown separately.