CVE-2020-26287 Information

Description

HedgeDoc is a collaborative platform for writing and sharing markdown. In HedgeDoc before version 1.7.1 an attacker can inject arbitrary script tags in HedgeDoc notes using mermaid diagrams. Our content security policy prevents loading scripts from most locations but www.google-analytics.com is allowed. Using Google Tag Manger it is possible to inject arbitrary JavaScript and execute it on page load. Depending on the configuration of the instance the attacker may not need authentication to create or edit notes. The problem is patched in HedgeDoc 1.7.1. As a workaround one can disallow www.google-analytics.com in the Content-Security-Policy header. Note that other ways to leverage the script tag injection might exist.

CVSS Vector

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

Reference

https://github.com/hedgedoc/hedgedoc/releases/tag/1.7.1 https://github.com/hedgedoc/hedgedoc/security/advisories/GHSA-g6w6-7xf9-m95p https://github.com/Alemmi/ctf-writeups/blob/main/hxpctf-2020/hackme/solution.md https://github.com/hackmdio/codimd/issues/1630 https://github.com/hedgedoc/hedgedoc/commit/58276ebbf4504a682454a3686dcaff88bc1069d4

Attack Complexity

LOW

Privileges Required

LOW

User Interaction Required

LOW

Scope

REQUIRED

Confidentiality Impact

CHANGED

Integrity Impact

HIGH

Availability Impact

HIGH

Base Score

NONE

Base Severity

8.7