What is CVE-2026-100674?

CVE-2026-100674 is a medium-severity vulnerability in Stoatchat, classified under CWE-180. CVSS score: 4.3/10. Published 2026-09-26.

How severe is CVE-2026-100674?

Medium severity. CVSS v3 base score is 4.3 out of 10.

Vulnerability in Stoatchat

CVE-2026-100674

stoatchat before 0.15.5 fails to revalidate usernames after Unicode sanitization, allowing attackers to create usernames with forbidden characters by submitting Unicode letters that transform into rejected characters. Attackers can bypass character allowlists and length limits to create reserved-name lookalikes, embed special characters, and exceed the 32-character storage limit.

Published 2026-09-26.

CVSS v3 metric

CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/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-180

References

github.com/stoatchat/stoatchat/security/advisories/GHSA-qcwh-c934-wrv5 (vendor-advisory)
www.vulncheck.com/advisories/stoatchat-before-0.15.5-username-validation-bypass… (third-party-advisory)

Frequently asked questions

What is CVE-2026-100674?: CVE-2026-100674 is a medium-severity vulnerability in Stoatchat, classified under CWE-180. CVSS score: 4.3/10. Published 2026-09-26.
How severe is CVE-2026-100674?: Medium severity. CVSS v3 base score is 4.3 out of 10.