# CVE-2026-100679: stoatchat MFA bypass via cross-account ticket validation

Source: https://junglewise.ai/threats/cve-2026-100679-stoatchat-before-0-15-5-fails-to-validate-that-mfa-tickets  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-26. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-100679 · Severity: high · CVSS 8.8 · Published 2026-09-26

stoatchat is a messaging and communication platform. An attacker can bypass multi-factor authentication (MFA) by using their own valid MFA ticket with a victim's session token, allowing them to disable two-factor authentication, view recovery codes, or delete accounts. This requires only that the attacker has obtained a victim's session token, making account takeover possible without knowing the victim's password.

## Quick answers

**Is CVE-2026-100679 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-100679 being exploited in the wild.

**How severe is CVE-2026-100679?** High severity, with a CVSS score of 8.8, published 26 September 2026.

**Which products and versions are affected?** Stoatchat before 0.15.5.

**Is there a fix for CVE-2026-100679?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-100679 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-100679?** Check whether you run Stoatchat at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The vulnerability exists in stoatchat's MFA ticket validation: while the MFATicket struct contains an account_id field, the API endpoints that consume MFA tickets (such as DELETE /auth/mfa/totp and POST /auth/mfa/recovery) never verify that the ticket's account_id matches the user ID resolved from the session token. An attacker with a valid session token from a compromised or leaked source can present their own MFA ticket, which is accepted for any sensitive operation, bypassing the second factor entirely. The flaw affects sensitive operations that require X-MFA-Ticket validation but do not separately re-verify the current password.

## Affected products

- stoatchat before 0.15.5

## Timeline

- 2026-09-11: disclosed
- 2026-09-26: advisory

## References

- [https://github.com/stoatchat/stoatchat/security/advisories/GHSA-gwg6-q3c3-97cx](https://github.com/stoatchat/stoatchat/security/advisories/GHSA-gwg6-q3c3-97cx)
- [https://www.vulncheck.com/advisories/stoatchat-before-0.15.5-mfa-bypass-via-cross-account-ticket](https://www.vulncheck.com/advisories/stoatchat-before-0.15.5-mfa-bypass-via-cross-account-ticket)

## Related threats

- [stoatchat denial of service in acknowledgement worker](https://junglewise.ai/threats/cve-2026-100675-stoatchat-versions-before-0-15-5-contain-a-denial-of-service)