Usermin through 2.570 contains a path traversal vulnerability in mailbox/detachall.cgi that allows remote unauthenticated attackers to write files outside the temporary directory via unsanitized attachment filenames. Attackers can email attachments with ../ sequences in filenames, and when the recipient downloads all attachments, files like ~/.forward are overwritten, enabling command execution.
https://hackmd.io/@leediay/H144QKY6zl
https://github.com/webmin/usermin/issues/142
https://github.com/webmin/usermin/commit/cb4614e8319e0932b10533a4d5606debf5f40e14
https://github.com/webmin/usermin/blob/2.570/mailbox/detachall.cgi#L43-L51
Published: 2026-11-06
Updated: 2026-11-12
Base Score: 10
Vector: CVSS2#AV:N/AC:L/Au:N/C:C/I:C/A:C
Severity: Critical
Base Score: 8.8
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Severity: High
Base Score: 8.6
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Severity: High
EPSS: 0.00984