---
id: CVE-2026-100678
title: >-
  stoatchat before 0.15.5 fails to enforce account-level attempt limits on MFA
  login challenges, allowing attackers who know a password to guess TOTP codes
  with only IP-based rate limiting
summary: >-
  stoatchat before 0.15.5 fails to enforce account-level attempt limits on MFA
  login challenges, allowing attackers who know a password to guess TOTP codes
  with only IP-based rate limiting. Attackers can reuse MFA challenge tickets
  across …
severity: medium
cvss: 6.5
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:N'
cwe:
  - CWE-307
vendor: stoatchat
product: stoatchat
affected:
  - stoatchat < 0.15.5
published: '2026-09-26'
updated: '2026-09-30'
sourceUpdated: '2026-09-30T16:17:00.153'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-100678'
references:
  - url: >-
      https://github.com/stoatchat/stoatchat/security/advisories/GHSA-6877-g673-f5r8
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/stoatchat-before-0.15.5-mfa-brute-force-via-insufficient-rate-limiting
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/stoatchat/stoatchat/security/advisories/GHSA-6877-g673-f5r8
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
tags:
  - nvd
  - cve.org
  - exploit-available
epss: 0.00299
epssPercentile: 0.22456
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-09-30T14:59:59.255314Z'
ingestedAt: '2026-09-26T13:33:20.910Z'
---

## Overview

stoatchat before 0.15.5 fails to enforce account-level attempt limits on MFA login challenges, allowing attackers who know a password to guess TOTP codes with only IP-based rate limiting. Attackers can reuse MFA challenge tickets across multiple failed attempts and distribute guesses across IP addresses to bypass rate limiting and gain account access.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.