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Cross-site Scripting (XSS)Weakness · CWE-79

CVE-2026-43900

CRITICAL · 9.3 CVSS v3.1 Published 2026-05-11
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
DeepChat is an open-source artificial intelligence agent platform that unifies models, tools, and agents. Prior to v1.0.4-beta.1, a Cross-Site Scripting (XSS) vulnerability exists due to a discrepancy between the backend validation layer and the frontend browser rendering engine. The SVGSanitizer (src/main/lib/svgSanitizer.ts) restricts script execution by scrubbing javascript: protocols using plain-text regular expressions. However, it fails to account for HTML entity decoding prior to Vue's v-html DOM insertion inside the SvgArtifact.vue component. By feeding an SVG artifact with obfuscated entities (e.g., javascript:alert(1)), an attacker can completely bypass the sanitizer, culminating in arbitrary JavaScript execution when a victim interacts with the rendered SVG Element. This vulnerability is fixed in v1.0.4-beta.1.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A stored XSS vulnerability exists in DeepChat's SVG sanitization. The SVGSanitizer uses plain-text regex to block javascript: protocols, but fails to handle HTML entity decoding that occurs before Vue's v-html DOM insertion in SvgArtifact.vue. Attackers can bypass the sanitizer using obfuscated entities like javascript:alert(1), achieving arbitrary JavaScript execution when victims interact with rendered SVG elements.

MitigationUpgrade to DeepChat v1.0.4-beta.1 or later, which fixes the entity decoding discrepancy in the SVG sanitization pipeline.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
Required
Scope
Changed
Confidentiality
High
Integrity
High
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify DeepChat version
    Check package.json, git tags, or the deployed DeepChat application version to determine if it is earlier than v1.0.4-beta.1. Compare against the fixed version.
    Affected if Installed version is earlier than v1.0.4-beta.1 and SVG rendering is in use
  2. Confirm SVG message rendering is enabled
    Inspect the application configuration or code to verify that SVG files or SVG content can be sent/received in chat messages. Look for SvgArtifact.vue component usage in the codebase.
    Affected if SVG content rendering is enabled and user-generated SVG can be posted to chat
  3. Inspect SVGSanitizer implementation
    Locate the SVGSanitizer file in the codebase. Check if the sanitization logic relies solely on regex pattern matching for javascript: without accounting for HTML entity decoding.
    Affected if Sanitizer uses plain-text regex without entity decoding handling
  4. Verify SvgArtifact.vue v-html usage
    Find SvgArtifact.vue and confirm it uses v-html to insert SVG content directly into the DOM. Check if entity decoding occurs before this insertion.
    Affected if SVG content is inserted via v-html without prior entity decoding normalization
  5. Test for XSS bypass
    Send a message containing an SVG with an obfuscated protocol such as javascript:alert(1) and observe if the JavaScript executes when viewing the message.
    Affected if The obfuscated payload executes JavaScript on interaction

A user is affected if DeepChat version is earlier than v1.0.4-beta.1 and SVG messages from other users can be rendered via v-html in the application.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade to DeepChat v1.0.4-beta.1 or later, which fixes the entity decoding discrepancy in the SVG sanitization pipeline.

Recommended fix High confidence

v1.0.4-beta.1

  1. 1. Identify the current DeepChat version in use by checking package.json or the deployed application
  2. 2. Upgrade the DeepChat installation to version v1.0.4-beta.1 or later
  3. 3. Verify the upgrade was successful by confirming the SVGSanitizer now properly handles HTML entity decoding before Vue v-html insertion
  4. 4. Test that SVG artifacts with obfuscated entities (e.g., javascript:alert(1)) are properly sanitized and cannot execute arbitrary JavaScript
Caveat As this is a beta version upgrade, review release notes for any other changes that may affect functionality

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory
  • Consultation3.0 h
  • Implementation4.0 h
  • Testing4.0 h
  • Review / QA2.0 h
13.0 hours of engineering $2,280
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-43900 in production — separate from our analysis above.

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What this is

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What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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