AnythingLLM — Prompt Injection (CVE-2026-41318)
Date: 2026-04
Affected: mintplexlabs/anythingllm
Attack vector: prompt-injection
Category: vulnerability-disclosure
Severity: Medium
CVE: CVE-2026-41318
CWE: CWE-116
CWE-1336
CWE-79
CVSS: 5.4 (CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:H/I:L/A:N)

AnythingLLM is an application that turns pieces of content into context that any LLM can use as references during chatting. Prior to version 1.12.1, AnythingLLM's in-chat markdown renderer has an unsafe custom rule for images that interpolates the markdown image's `alt` text into an HTML `alt="..."` attribute without any HTML encoding. Every call-site in the app wraps `renderMarkdown(...)` with `DOMPurify.sanitize(...)` as defense-in-depth — except the `Chartable` component, which renders chart captions with no sanitization. The chart caption is the natural-language text the LLM emits around a `create-chart` tool call, so any attacker who can influence the LLM's output — most cheaply via indirect prompt injection in a shared workspace document, or directly if they can create a chart record in a multi-user workspace — can trigger stored DOM-level XSS in every other user's browser when they open that conversation. AnythingLLM chat history is loaded server-side via `GET /api/workspace/:slug/chats` and rendered directly into the chat UI. Version 1.12.1 contains a patch for this issue.


Mitigations:

Architectural layers (MAESTRO):