@asymmetric-effort/nogginlessdom vulnerable to ReDoS via user-controlled regex in HTMLInputElement pattern validation

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

6.9 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N · score source

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

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)

Published by the source

2 Jul 2026, 20:20 UTC

Last modified by the source

10 Sep 2026, 03:50 UTC

Source last checked

26 Oct 2026, 12:56 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-x4hg-hfwf-p9mw

2. Revision 2 · amended · 25 Oct 2026

   Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-x4hg-hfwf-p9mw

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# Patch Next advisory brief: GHSA-x4hg-hfwf-p9mw

Advisory: @asymmetric-effort/nogginlessdom vulnerable to ReDoS via user-controlled regex in HTMLInputElement pattern validation
IDs: GHSA-x4hg-hfwf-p9mw
Record: https://patchnext.com/advisories/ghsa-x4hg-hfwf-p9mw (revision 3, source checked 26 Oct 2026, 12:56 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: @asymmetric-effort/nogginlessdom 0.0.22. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm @asymmetric-effort/nogginlessdom: affected <= 0.0.21; fixed in 0.0.22

## Suggested inspection (read-only)
- `npm ls @asymmetric-effort/nogginlessdom --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on @asymmetric-effort/nogginlessdom.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-x4hg-hfwf-p9mw (OSV record GHSA-x4hg-hfwf-p9mw lists affected ranges: npm @asymmetric-effort/nogginlessdom >=0 <0.0.22 (fixed))
- Verified: https://github.com/advisories/GHSA-x4hg-hfwf-p9mw (GitHub-reviewed advisory GHSA-x4hg-hfwf-p9mw lists affected ranges: npm @asymmetric-effort/nogginlessdom >=0 <=0.0.21)

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