50/100 CVSS 8.7 🔴 CVE ANALYSISPublished: June 17, 2026

Open WebUI: Stored XSS in Mermaid Markdown Preview

## Summary Open WebUI renders Mermaid blocks from Markdown files in the file preview panel and inserts the generated SVG into the DOM using `innerHTML`. Because Mermaid is configured with `securityLevel: 'loose'`, attacker-controlled Mermaid content can be rendered unsafely in this flow. A working payload was validated through the Markdown preview ...

8.7

CVSS Score

MEDIUM

Threat Level

Priority /100

TBD

Exploited ITW

Monitor

CISA Status

Sources

🔵

HIGH-PRIORITY SECURITY ADVISORY — Priority Score: 50/100

CVSS 8.7 MEDIUM. SENTINEL APEX recommends immediate patch evaluation. Intelligence from 1 confirmed source(s).

📋 Executive Summary

⚡ Analyst Assessment — SENTINEL APEX v4.0

CYBERDUDEBIVASH SENTINEL APEX has confirmed a MEDIUM-tier threat intelligence signal for CVE-2026-54011 affecting pip open-webui. Composite threat score: 50/100. Intelligence corroborated across 1 source(s): github_advisories. CVSS base score: 8.7. Exploitation probability assessed as HIGH based on vulnerability characteristics.

Intelligence sources: github_advisories

⚠️ Business Impact Analysis

⚠️ Privilege escalation — local attacker can become SYSTEM/root

🔗 Attack Chain Analysis

Step-by-step attack chain based on observed TTPs and vulnerability characteristics:

#	Phase	Attacker Action	MITRE
1	Reconnaissance	Attacker identifies exposed open-webui instances via Shodan, Censys, or targeted scanning	`TA0043`
2	Initial Access	Exploitation of CVE-2026-54011 in pip open-webui	`T1190`
3	Privilege Escalation	Local privilege escalation to SYSTEM/root for full control	`T1068`
4	Persistence	Backdoor, scheduled task, or new admin account created for persistent access	`T1053`
5	Command & Control	Attacker establishes persistent C2 channel using HTTPS or DNS tunneling	`T1071`
6	Impact / Objectives	Intellectual property theft, espionage, cryptomining, or preparation for future attack stage	`T1657`

⚠ Deep Dive Analysis

This high-severity vulnerability in pip open-webui (CVSS 8.7) represents a significant attack surface. SENTINEL APEX assesses exploitation to be technically feasible with moderate effort. Organizations running open-webui in internet-facing or privileged positions face immediate risk.

SENTINEL APEX URGENCY: HIGH. Score: 50/100 MEDIUM. Patch before exploitation activity begins.

🎯 MITRE ATT&CK Mapping

Category	Mapping
Primary Tactic	ML Attack Staging
Primary Technique	AML.T0040 — ML Attack Staging
Sub-Technique	AML.T0000 — AI/ML System Enumeration
Weakness (CWE)	CWE-79
Intel Type	🔴 CVE ANALYSIS
Source(s)	github_advisories

🔴 CVE Reference

CVE ID	Reference	Score
CVE-2026-54011	NVD →	8.7
CVE-2026-54011	NVD →	8.7

🏷️ Indicators of Compromise — Enriched IOC Feed

Normalized IOCs with confidence scoring. Block immediately across all enforcement points. SOC Pro subscribers receive enriched IOC bundles with full attribution and STIX/TAXII feeds.

Indicator Value	Type	Confidence	First Seen
9bd84258d09eefe7bf975878fb0e31a5dadfe0f8	sha1	90%	2026-06-17
https://github.com/open-webui/open-webui/blob/9bd84258d09eefe7bf975878fb0e31a5da	url	82%	2026-06-17

🔍 Detection Rules — Sigma (SIEM)

Deploy to Splunk, Elastic, Microsoft Sentinel, or QRadar. SOC Pro subscribers receive pre-compiled SIEM-native query packs updated with each pipeline run.

Sigma YAMLtitle: CVE-2026-54011 Exploitation Attempt — pip open-webui
id: 75775043495b635c-faf4
status: experimental
description: Detects exploitation of CVE-2026-54011 in pip open-webui. Priority: MEDIUM. Score: 50/100
author: CYBERDUDEBIVASH SENTINEL APEX v4.0 (bivash@cyberdudebivash.com)
date: 2026-06-17
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2026-54011
    - https://blog.cyberdudebivash.in/
tags:
    - attack.initial_access
    - attack.t1190
    - cve-2026-54011
    - cve-2026-54011
logsource:
    category: webserver
detection:
    keywords:
        - 'CVE-2026-54011'
        - 'CVE-2026-54011'
        - 'cve-2026-54011'
    condition: keywords
falsepositives:
    - Security scanners
level: high

📡 Detection Rules — YARA (Endpoint)

Deploy to endpoint detection platforms. Enterprise subscribers receive tuned, FP-validated YARA rule packs.

YARArule CVE_2026_54011_Exploitation {
    meta:
        description = "Detects artifacts related to CVE-2026-54011 exploitation in pip open-webui"
        author      = "CYBERDUDEBIVASH SENTINEL APEX v4.0"
        date        = "2026-06-17"
        severity    = "HIGH"
        cvss        = "8.7"
        priority    = "50/100"
        threat_level = "MEDIUM"
        reference   = "https://nvd.nist.gov/vuln/detail/CVE-2026-54011"
    strings:
        $id_str  = "CVE-2026-54011" ascii nocase
        $product = "open_webui" ascii nocase wide
    condition:
        any of them
}

🛡️ SOC Response Playbook

1IMMEDIATE (0-1hr): Identify all instances of open-webui in your environment via CMDB/asset inventory
2IMMEDIATE: Block all 2 IOCs in this report at firewall, proxy, DNS, and EDR simultaneously
3IMMEDIATE (0-1hr): Apply vendor patch — no maintenance window exception for MEDIUM threats
4IMMEDIATE (1-2hr): If no patch available: implement WAF rules, ACLs, or network-level compensating controls
5SHORT-TERM (2-4hr): Deploy Sigma detection rule to SIEM — validate alert generation in test environment
6SHORT-TERM (4-8hr): Review logs for exploitation indicators (anomalous open-webui requests, error spikes)
7SHORT-TERM (8-24hr): Hunt for post-exploitation: new admin accounts, scheduled tasks, lateral movement
8MONITOR: Subscribe to pip security advisories for patch updates
9ONGOING: Track SENTINEL APEX intelligence feed for follow-on campaigns targeting open-webui

📎 Intelligence References

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Related Resources — SENTINEL APEX

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⚡ CYBERDUDEBIVASH SENTINEL APEX v4.0

Intelligence report generated by CYBERDUDEBIVASH SENTINEL APEX v4.0
Report ID: SENTINEL-CVE-2026-54011-2026-06-17 | Priority: 50/100 MEDIUM | Sources: 1
© 2026 CYBERDUDEBIVASH PRIVATE LIMITED
Republication requires written attribution to CYBERDUDEBIVASH SENTINEL APEX

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