Cross-site scripting in Group Office - CVE-2026-125389
Published: November 10, 2026 / Updated: November 10, 2026
Vulnerability identifier: #VU164334
CSH Severity: Medium
CVSS v4: 5.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N]
CVE-ID: CVE-2026-125389
CWE-ID: CWE-79
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote user to execute JavaScript in the Group-Office origin and take over a victim's account.
The vulnerability exists due to incomplete event-handler filtering in the email viewer when rendering message HTML directly into the application document. A remote user can send HTML email containing <svg/onload=alert(document.cookie)> and induce the victim to view the filtered message, or exploit check bypasses for senders matching contacts in writable addressbooks or messages in sent/drafts folders, to execute JavaScript when the message is opened.
Affected software
Group Office
How to mitigate CVE-2026-125389
Install security update from vendor's website.
Group Office - addressed in versions 6.8.181, 26.0.58