# CVE-2026-100679: stoatchat before 0.15.5 MFA Bypass via Cross-Account Ticket

> Attackers can bypass MFA by using their own ticket with a victim's session token to disable TOTP or view recovery codes.

- **Severity:** High 7.1 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/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:** 26 Sep 2026
- **Updated:** 28 Sep 2026
- **Also known as:** GHSA-2jwx-p7f6-684c, GHSA-gwg6-q3c3-97cx

## What is CVE-2026-100679?

CVE-2026-100679 is a high-severity authentication bypass vulnerability in stoatchat, published on 26 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

stoatchat before 0.15.5 fails to validate that MFA tickets belong to the authenticated user, allowing attackers to bypass MFA by using their own valid ticket with another user's session token. Attackers can obtain a ticket from their own account and use it with a victim's session token to disable TOTP, view recovery codes, or perform other sensitive operations without providing the victim's credentials.

Weakness: CWE-639 (Authorization Bypass Through User-Controlled Key)

## Which versions are affected by CVE-2026-100679?


## How do I fix CVE-2026-100679?

No fix has been published for CVE-2026-100679 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-100679 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-100679 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-100679 and fix it if it is affected.

What it is: CVE-2026-100679 is a high-severity authentication bypass vulnerability in stoatchat, published on 26 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-100679 exists.

Affected product: stoatchat. 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-2026-100679/ (Markdown: https://insights.sbomify.com/CVE-2026-100679/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-100679
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-100679
- OSV: https://osv.dev/vulnerability/CVE-2026-100679

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-100679/
Summaries are generated and may contain mistakes; the official description above is the record.