CVE-2026-100674 (CVSS 4.3)

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.

Is your site exposed to CVE-2026-100674?

Run a free security scan — no signup, results in seconds.

CVSS v3.1 Score

4.3

MEDIUM

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

EPSS — Exploit Prediction

0.0023

Probability of exploitation

0.14%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-180 CWE-180

References

Other 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

Frequently Asked Questions

What is 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. It has a CVSS v3.1 base score of 4.3 (MEDIUM).

How severe is CVE-2026-100674? +

CVE-2026-100674 has a CVSS v3.1 score of 4.3 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0023, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-100674? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

CVE-2025-29787

`zip` is a zip library for rust which supports reading and writing of simple ZIP files. In the archive extraction …

CVE-2026-82481

The cohttp package before 6.3.0 for OCaml allows directory traversal.

CVE-2026-45022

go-git is an extensible git implementation library written in pure Go. Prior to 5.19.0 and 6.0.0-alpha.3, go-git may parse malformed …

CVE-2026-118662

Vite is a frontend tooling framework for JavaScript. From 6.4.4 until 6.4.5, the Vite development server can evaluate server.fs.deny before …

CVE-2026-110846

n8n before 2.41.4 and 2.42.x before 2.42.1 contains a signature bypass in the waiting-webhook endpoint, which selects Send-and-Wait validation before …

CVE-2026-61812

ModSecurity is an open source, cross platform web application firewall (WAF) engine for Apache, IIS and Nginx. Prior to 2.9.15 …