What is CVE-2026-100678?

CVE-2026-100678 is a medium-severity vulnerability in Stoatchat, classified under Improper Restriction of Excessive Authentication Attempts. CVSS score: 6.5/10. Published 2026-09-26.

How severe is CVE-2026-100678?

Medium severity. CVSS v3 base score is 6.5 out of 10.

Vulnerability in Stoatchat

CVE-2026-100678

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.

Published 2026-09-26.

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:N.

EPSS exploit prediction

No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.

Affected products

Stoatchat

Weakness classification (CWE)

CWE-307 — Improper Restriction of Excessive Authentication Attempts

References

github.com/stoatchat/stoatchat/security/advisories/GHSA-6877-g673-f5r8 (vendor-advisory)
www.vulncheck.com/advisories/stoatchat-before-0.15.5-mfa-brute-force-via-insuff… (third-party-advisory)

Frequently asked questions

What is CVE-2026-100678?: CVE-2026-100678 is a medium-severity vulnerability in Stoatchat, classified under Improper Restriction of Excessive Authentication Attempts. CVSS score: 6.5/10. Published 2026-09-26.
How severe is CVE-2026-100678?: Medium severity. CVSS v3 base score is 6.5 out of 10.