CVE-2026-100674

MEDIUM 4.3

stoatchat before 0.15.5 Username Validation Bypass via Unicode Sanitization

CVSS Score

4.3

EPSS Score

0.0%

EPSS Percentile

0th

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.

CWE	CWE-180
Vendor	stoatchat
Product	stoatchat
Published	Sep 26, 2026

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CVSS v3 Breakdown

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

Low

Availability

None

Affected Versions

stoatchat / stoatchat

0 < 0.15.5

References

NVD ↗ CVE.org ↗ EPSS Data ↗

github.com: https://github.com/stoatchat/stoatchat/security/advisories/GHSA-qcwh-c934-wrv5 vulncheck.com: https://www.vulncheck.com/advisories/stoatchat-before-0.15.5-username-validation-bypass-via-unicode-sanitization