XSS in Hedgedoc
CVE-2021-21259
HedgeDoc is open source software which lets you create real-time collaborative markdown notes. In HedgeDoc before version 1.7.2, an attacker can inject arbitrary JavaScript into a HedgeDoc note, which is executed when the note is viewed in slide mode. Depending on the configuration of the instance, the attacker may not need authentication to create or edit notes. The problem is patched in HedgeDoc 1.7.2. As a workaround, disallow loading JavaScript from 3rd party sites using the `Content-Security-Policy` header. Note that this will break some embedded content.
Vulnerability class: XSS (Cross-Site Scripting)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.4 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:H/A:N.
EPSS exploit prediction
EPSS: 0.014 (70.4th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 70th percentile — 70.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.014 · newest: 0.014 · change: 0.000
Affected products
- Hedgedoc — versions < 1.7.2
Weakness classification (CWE)
References
- github.com/hedgedoc/hedgedoc/security/advisories/GHSA-44w9-vm8p-3cxw (Third Party Advisory)
- github.com/hedgedoc/hedgedoc/releases/tag/1.7.2 (Third Party Advisory, Release Notes)
- github.com/hedgedoc/hedgedoc/commit/35b0d39a12aa35f27fba8c1f50b1886706e7efef (Patch, Third Party Advisory)
- github.com/hackmdio/codimd/issues/1648 (Exploit, Patch, Third Party Advisory)
Frequently asked questions
- What is CVE-2021-21259?
- CVE-2021-21259 is a high-severity vulnerability in Hedgedoc, classified under Cross-site Scripting. CVSS score: 7.4/10. Published 2021-01-22.
- How severe is CVE-2021-21259?
- High severity. CVSS v3 base score is 7.4 out of 10.