CVE-2026-100679

stoatchat before 0.15.5 MFA Bypass via Cross-Account Ticket

Published Sep 26, 2026 CVSS 4.0 · 7.1 High EPSS < 1% KEV · Not listed
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.

Analysis

AI-generated

Technical impact

stoatchat versions prior to 0.15.5 do not verify that a submitted MFA ticket belongs to the user who is authenticated, so attackers can submit a ticket issued for their own account together with a valid session token belonging to another user. This flaw allows the attacker to disable TOTP, view recovery codes, and carry out other sensitive operations without the victim’s credentials.

Affected Systems

The vulnerability targets the stoatchat application for all releases before 0.15.5. Users running these older versions are exposed if they have MFA enabled and are using the built‑in ticket system for authentication.

Risk and Exploitability

The reported CVSS score of 7.1 indicates a high impact with moderate exploitation complexity. EPSS data is not available, and the flaw is not listed in CISA’s KEV catalog. Exploitation requires an attacker to possess a valid MFA ticket from an account they control and the victim’s session token, a relatively straightforward requirement. Successful use of the vulnerability gives the attacker full control over the victim’s account and the ability to perform all actions that the account owner can normally do.

Remediation

No solution or workaround provided in the CVE record.

OpenCVE Recommended Actions

  • Upgrade stoatchat to version 0.15.5 or later, which validates MFA tickets against the owning user.
  • Revoke existing MFA tokens after the upgrade and force users to re‑configure their two‑factor authentication.
  • Implement monitoring for atypical session activity and consider tightening session token lifetimes or adding IP restrictions for privileged actions.

Generated by OpenCVE AI on September 26, 2026 at 16:38 UTC.

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Stoatchat
Stoatchat stoatchat
Vendors & Products Stoatchat
Stoatchat stoatchat
Type Values Removed Values Added
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.
Title stoatchat before 0.15.5 MFA Bypass via Cross-Account Ticket
Weaknesses CWE-639
References
Metrics cvssV3_1

{'score': 8.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'}

cvssV4_0

{'score': 7.1, 'vector': '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'}

Weaknesses
  • CWE-639

    Authorization Bypass Through User-Controlled Key

Sources

Status
PUBLISHED
Assigner
VulnCheck
Published
Updated
Sep 28, 2026, 6:03 PM
Reserved
Sep 26, 2026, 2:36 AM
Status
Deferred
Published
Sep 26, 2026, 2:16 PM
Modified
Sep 28, 2026, 6:17 PM