# CVE-2026-43900: DeepChat: Persistent DOM XSS via HTML Entity Encoding in `<antArtifact>` SVG Rendering (Bypass of `svgSanitizer.ts`)

> Attackers can execute arbitrary JavaScript in victim browsers by bypassing SVG sanitization via HTML entity encoding in DeepChat.

- **Severity:** Critical 9.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 11 May 2026
- **Updated:** 12 May 2026
- **Also known as:** GHSA-7r59-67v3-3mgp

## What is CVE-2026-43900?

CVE-2026-43900 is a critical cross-site scripting vulnerability in ThinkInAIXYZ deepchat, published on 11 May 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

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., j&#x61;vascript: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.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2026-43900?


## How do I fix CVE-2026-43900?

No fix has been published for CVE-2026-43900 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-43900 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-43900 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-43900 and fix it if it is affected.

What it is: CVE-2026-43900 is a critical cross-site scripting vulnerability in ThinkInAIXYZ deepchat, published on 11 May 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-43900 exists.

Affected product: ThinkInAIXYZ deepchat. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-43900/ (Markdown: https://insights.sbomify.com/CVE-2026-43900/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-43900
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-43900
- OSV: https://osv.dev/vulnerability/CVE-2026-43900

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-43900/
Summaries are generated and may contain mistakes; the official description above is the record.