Path Traversal in Webmin Usermin
CVE-2026-123621
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.
Vulnerability class: Path Traversal (Directory Traversal)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
Weakness classification (CWE)
References
- github.com/webmin/usermin (product)
- github.com/webmin/usermin/blob/2.570/mailbox/detachall.cgi (technical-description)
- github.com/webmin/usermin/commit/cb4614e8319e0932b10533a4d5606debf5f40e14 (patch)
- github.com/webmin/usermin/issues/142 (issue-tracking)
- hackmd.io/@leediay/H144QKY6zl (technical-description)
- www.vulncheck.com/advisories/usermin-through-2.570-path-traversal-file-write-vi… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-123621?
- CVE-2026-123621 is a high-severity vulnerability in Webmin Usermin, classified under Path Traversal. CVSS score: 8.8/10. Published 2026-11-06.
- How severe is CVE-2026-123621?
- High severity. CVSS v3 base score is 8.8 out of 10.