CVE-2026-109290
HIGH 8.4Open WebUI from 0.11.1 before 0.11.4 contains a stored cross-site scripting vulnerability in DocxPreview.svelte that allows authenticated users to execute script by uploading crafted DOCX attachments. Attackers can embed an OOXML altChunk HTML part or script-scheme hyperlink to steal a previewing administrator's session token from local storage and take over the instance.
Severe if exploited (CVSS 8.4), but no known exploitation and low modeled probability. Patch on a normal cadence.
Exploitation likelihood
0.3%chance of exploitation in 30 days · 24th percentile
Impact if exploited
8.4CVSS 4.0 · HIGH
- ConfidentialityHigh
- IntegrityHigh
- AvailabilityNone
What an attacker needs
- ✓Access: Reachable over the network — no local access needed
- ⚠Privileges: Requires a low-privilege account
- ⚠User interaction: Requires active user interaction
- ✓Complexity: No special conditions — reliably repeatable
- ✓Requirements: No special attack requirements
✓ lowers the bar for an attacker · ⚠ raises it
Proof of concept
No public PoC is currently catalogued.
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Data snapshot:
Weakness (CWE)
- CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
- CWE-1021: Improper Restriction of Rendered UI Layers or Frames
CVSS vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
References and research data (JSON)
All CVSS metrics
- HIGH 8.4 v4.0 · CNA Primary
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N - HIGH 8.7 v3.1 · CNA Primary
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N - HIGH 8.4 v4.0 · NVD Secondary
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - HIGH 8.7 v3.1 · NVD Primary
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N
References
Exploit-tagged references (not proof of a PoC)
- https://github.com/open-webui/open-webui/security/advisories/GHSA-f9xp-mfmq-x6cg CVE record · VulnCheck · Updated 2026-10-23T21:57:53.874Z
CVE record · CISA-ADP · Updated 2026-10-13T18:08:17.883Z
NVD · CVE-2026-109290 · Updated 2026-10-23T22:16:53.993
Advisories
- https://www.vulncheck.com/advisories/open-webui-0.11.1-before-0.11.4-stored-xss-via-docx-preview CVE record · VulnCheck · Updated 2026-10-23T21:57:53.874Z
NVD · CVE-2026-109290 · Updated 2026-10-23T22:16:53.993 - https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-97592 EUVD · EUVD-2026-97592