Vulnerability · Published Sep 26, 2026 · Assigned by VulnCheck

CVE-2026-100674stoatchat before 0.15.5 Username Validation Bypass via Unicode Sanitization

Medium 4.3

In plain English

A medium-severity security flaw in stoatchat from stoatchat. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 14% of all known vulnerabilities).

Severity (CVSS 3.1)4.3Medium

Exploit odds (30 days)0.2%top 85.6% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

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.

Affected products (as reported)

Vendor	Product	Versions
stoatchat	stoatchat	0 – before 0.15.5

Weakness: CWE-180 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N

References

GitHub Security Advisory (GHSA-qcwh-c934-wrv5) vendor-advisory
VulnCheck Advisory: stoatchat before 0.15.5 Username Validation Bypass via Unicode Sanitization third-party-advisory