Cross-site scripting in Etherpad - #VU151606
Published: September 22, 2026
Vulnerability identifier: #VU151606
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: N/A
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 script in a consumer's origin.
The vulnerability exists due to improper neutralization of input during web page generation in the author colors branch of getHTMLFromAtext when exporting diff HTML. A remote attacker can import a crafted .etherpad file to inject arbitrary HTML or script into the exported diff HTML.
User interaction is required because a consumer must render the exported diff HTML.
Affected software
Etherpad
Remediation
Install security update from vendor's website.
Etherpad - update to 3.3.4