Cross-site scripting in HedgeDoc - CVE-2021-21259
Published: January 15, 2021 / Updated: April 25, 2026
Vulnerability identifier: #VU127918
CSH Severity: Medium
CVSS v4: 5.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N]
CVE-ID: CVE-2021-21259
CWE-ID: CWE-79
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to execute arbitrary JavaScript in a victim's browser.
The vulnerability exists due to cross-site scripting in slide mode when rendering a crafted note. A remote attacker can inject arbitrary JavaScript into a note to execute arbitrary JavaScript in a victim's browser.
Depending on the instance configuration, authentication may not be required to create or edit notes.
Affected software
HedgeDoc
How to mitigate CVE-2021-21259
Install security update from vendor's website.
HedgeDoc - update to 1.7.2