stoatchat before 0.15.5 Username Validation Bypass via Unicode Sanitization (CVE-2026-100674) | HOL Guard CVE

Medium · CVSS 5.3CVE-2026-100674

stoatchat before 0.15.5 Username Validation Bypass via Unicode Sanitization

Answer in brief

CVE-2026-100674 records a Medium severity (CVSS 5.3) vulnerability in stoatchat before 0.15.5 Username Validation Bypass via Unicode Sanitization. The current sources do not mark it as known exploited. The current feed maps stoatchat/stoatchat (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 26, 2026Updated Sep 26, 2026Source checked Sep 26, 2026First seen by HOL Sep 26, 2026Material review Sep 26, 2026

Upstream Advisory

Key facts

Risk: Medium · CVSS 5.3
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Available

Why this deserves its current priority

CVSS is 5.3. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps stoatchat/stoatchat (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
stoatchat/stoatchatgeneric	>=0 <0.15.5	0.15.5

Recommended response

Check inventory. Check lockfiles and deployed manifests for stoatchat/stoatchat.
Review the reported fix. Update stoatchat/stoatchat to 0.15.5 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 26, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 26, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 26, 2026

Sources and claim methodology

Upstream source 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.

Quoted source text, attributed separately from HOL analysis.