# CVE-2026-123621: Usermin through 2.570 Path Traversal File Write via detachall.cgi


- **Severity:** High 8.6 (`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`)
- **Exploited in the wild:** Not known
- **Fix available:** No
- **Published:** 6 Nov 2026
- **Updated:** 6 Nov 2026
- **Also known as:** GHSA-6rhc-3jj8-rcqx

## What is CVE-2026-123621?

CVE-2026-123621 is a high-severity vulnerability in webmin usermin, published on 6 Nov 2026. 

### Official description

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.

Weakness: CWE-22 (Improper Limitation of a Pathname to a Restricted Directory)

## Which versions are affected by CVE-2026-123621?


## How do I fix CVE-2026-123621?

No fix has been published for CVE-2026-123621 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-123621 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-123621 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-123621 and fix it if it is affected.

What it is: CVE-2026-123621 is a high-severity vulnerability in webmin usermin, published on 6 Nov 2026. 
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-123621 exists.

Affected product: webmin usermin. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-123621/ (Markdown: https://insights.sbomify.com/CVE-2026-123621/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-123621
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-123621
- OSV: https://osv.dev/vulnerability/CVE-2026-123621

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-123621/
Summaries are generated and may contain mistakes; the official description above is the record.