# GHSA-x4hg-hfwf-p9mw: @asymmetric-effort/nogginlessdom vulnerable to ReDoS via user-controlled regex in HTMLInputElement pattern validation

> Attackers can cause denial of service by injecting malicious regex patterns into HTML input validation, freezing the application event loop.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 2 Jul 2026

## What is GHSA-x4hg-hfwf-p9mw?

GHSA-x4hg-hfwf-p9mw is a denial of service vulnerability in @asymmetric-effort/nogginlessdom, published on 2 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

## Summary

The `HTMLInputElement.checkValidity()` method constructed a `RegExp` directly from the user-controlled `pattern` property without any sanitization or timeout protection. This allowed an attacker to inject a regex with catastrophic backtracking, freezing the event loop.

## Fix

Fixed in commit https://github.com/asymmetric-effort/NogginLessDom/commit/25a3cbac665fae5663f8b71c073b80c3152dbe7b on `main`. Added:
- Pattern length limit (1024 characters)
- Nested quantifier detection (`hasNestedQuantifiers`) that rejects patterns like `(a+)+` before constructing the regex
- Patterns exceeding limits are treated as non-matching (safe default)

## Which versions are affected by GHSA-x4hg-hfwf-p9mw?

2 open source packages ship an affected version, including @asymmetric-effort/nogginlessdom.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `@asymmetric-effort/nogginlessdom` | npm | All versions | 0.0.22 |
| `@asymmetric-effort/nogginlessdom` | npm | All versions | 0.0.22 |

## How do I fix GHSA-x4hg-hfwf-p9mw?

Upgrade @asymmetric-effort/nogginlessdom to 0.0.22 or later.

## Is GHSA-x4hg-hfwf-p9mw being exploited?

There is no known exploitation of GHSA-x4hg-hfwf-p9mw in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for GHSA-x4hg-hfwf-p9mw and fix it if it is affected.

What it is: GHSA-x4hg-hfwf-p9mw is a denial of service vulnerability in @asymmetric-effort/nogginlessdom, published on 2 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of GHSA-x4hg-hfwf-p9mw in the wild and no public exploit code.

Affected packages and fixed versions:
- @asymmetric-effort/nogginlessdom (npm): affected all versions; fixed in 0.0.22
- @asymmetric-effort/nogginlessdom (npm): affected all versions; fixed in 0.0.22

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/GHSA-x4hg-hfwf-p9mw/ (Markdown: https://insights.sbomify.com/GHSA-x4hg-hfwf-p9mw/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/GHSA-x4hg-hfwf-p9mw

---
From sbomify Insights: https://insights.sbomify.com/GHSA-x4hg-hfwf-p9mw/
Summaries are generated and may contain mistakes; the official description above is the record.