---
id: "CVE-2026-126569"
page: "https://infrastack.ai/live/CVE-2026-126569"
kind: "vulnerability"
aliases: ["CVE-2026-126569"]
title: "Mbin: stored cross-site scripting through Markdown image alt text"
severity: "medium"
cvss: 5.4
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["federated-forum", "mbin", "package", "self-hosted"]
not_affected_if: ["no-user-generated-content", "version-1.11.1-or-later"]
published_at: "2026-11-11T03:16:51+00:00"
first_seen_at: "2026-11-11T03:25:00+00:00"
updated_at: "2026-11-11T03:26:26+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-126569", "first_seen_at": "2026-11-11T03:25:00+00:00"}]
exploit_sources: []
---

# Mbin: stored cross-site scripting through Markdown image alt text

Link for people: https://infrastack.ai/live/CVE-2026-126569 (this .md is for agents)

Mbin, a Markdown-based federated forum, renders nested Markdown image alt text and URLs without HTML escaping. An authenticated user can embed HTML in an image alt text inside a link in entries, comments, posts, messages or bios, so the script runs in other users' browsers.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the installed Mbin version; versions from 1.2.1 up to but not including `1.11.1` are listed as affected.
- Confirm whether untrusted users can post content that is rendered to other users.

## Fix

- Mbin: move to `1.11.1` or later.

## Timeline

- 2026-11-11T03:25:00+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-126569

## Documents

- [advisory] Vendor advisory: github.com https://github.com/MbinOrg/mbin/security/advisories/GHSA-g3r9-j6w4-2257
- [advisory] Third-party advisory: www.vulncheck.com https://www.vulncheck.com/advisories/mbin-1.2.1-before-1.11.1-stored-xss-via-markdown-image-nested-in-link
- [fix] Patch: github.com https://github.com/MbinOrg/mbin/commit/736fd39fe9cd59f5d51636d25e1857d88ddbd0bd
- [fix] Release notes: github.com https://github.com/MbinOrg/mbin/releases/tag/v1.11.1

## From the sources

Mbin 1.2.1 before 1.11.1 contains a stored cross-site scripting vulnerability in EmbedElement::buildDestructed() that renders nested Markdown image alt text and URL without HTML escaping. Authenticated users can embed HTML in the alt text of an image inside a link in entries, comments, posts, messages, or bios to run script in viewers' browsers.

---

_Free to read, with fair use of about 60 pages a minute. For higher limits or API access: sales@infrastack.ai_