# CVE-2026-84831: Mandatory MFA bypass before enrollment

> Attackers with valid passwords for unenrolled MFA accounts can bypass second-factor authentication and access privileged functionality in SEPPmail Secure Email Gateway.

- **Severity:** High 7.7 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 3 Sep 2026
- **Updated:** 8 Oct 2026
- **Also known as:** GHSA-4fw6-qxc4-gqgq

## What is CVE-2026-84831?

CVE-2026-84831 is a high-severity authentication bypass vulnerability in SEPPmail Secure Email Gateway (SEG), published on 3 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

SEPPmail Secure Email Gateway before 15.0.7 creates a fully privileged session before required multi-factor authentication enrollment is completed. An attacker with the password for an MFA-required but unenrolled account can access protected functionality without providing a second factor.

Weakness: CWE-306 (Missing Authentication for Critical Functionality), CWE-287 (Improper Authentication)

## Which versions are affected by CVE-2026-84831?


## How do I fix CVE-2026-84831?

No fix has been published for CVE-2026-84831 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-84831 being exploited?

There is no known exploitation of CVE-2026-84831 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-84831 and fix it if it is affected.

What it is: CVE-2026-84831 is a high-severity authentication bypass vulnerability in SEPPmail Secure Email Gateway (SEG), published on 3 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-84831 in the wild and no public exploit code.

Affected product: SEPPmail Secure Email Gateway (SEG). 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-2026-84831/ (Markdown: https://insights.sbomify.com/CVE-2026-84831/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-84831
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-84831
- OSV: https://osv.dev/vulnerability/CVE-2026-84831

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-84831/
Summaries are generated and may contain mistakes; the official description above is the record.