Usermin through 2.570 XSS via mailbox detach.cgi type Parameter

Advisories

Usermin through 2.570 XSS via mailbox detach.cgi type Parameter

Severity: medium
Date: 11/6/2026
Affecting: usermin <= 2.570
CVE: CVE-2026-123622
CWE: CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CVSS: 5.1
CVSS V4 Vector: 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
References: GitHub Issue #142
https://github.com/webmin/usermin
Fix commit c5c43b9
detach.cgi content type handling
Researcher write-up
Credit: leediay153 from Viettel Post, Ilia Ross (iliaross)
Description: Usermin through 2.570 contains a cross-site scripting vulnerability in mailbox/detach.cgi that allows remote attackers to execute script by supplying an arbitrary type parameter that bypasses JavaScript filtering. Attackers can email an HTML attachment containing script and lure recipients to a detach.cgi link with type=text/html to run script in the victim's authenticated Usermin session.

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