XSS in Hedgedoc

CVE-2020-26287

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.

Vulnerability class: XSS (Cross-Site Scripting)

Published · last modified .

CVSS v3 metric

CVSS v3 base score 8.7 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N.

EPSS exploit prediction

EPSS: 0.015 (72.6th percentile), scored .

Low probability of exploitation in the next 30 days, but still tracked. 73rd percentile — 72.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2020-26287: held from 0.014 to 0.015.

EPSS over last 30 days · oldest: 0.014 · newest: 0.015 · change: +0.000

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2020-26287?
CVE-2020-26287 is a high-severity vulnerability in Hedgedoc, classified under Cross-site Scripting. CVSS score: 8.7/10. Published 2020-12-29.
How severe is CVE-2020-26287?
High severity. CVSS v3 base score is 8.7 out of 10.