What’s Vulnerable › Vulnerabilities

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

• Severity: medium (CVSS 4.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-26 · updated 2026-09-30
• Weakness: CWE-180

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

• stoatchat: before 0.15.5 — fixed in 0.15.5

How to fix

Upgrade to a fixed version: stoatchat 0.15.5. Check the vendor advisory for mitigations.

References

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

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