html-parse-stringify and html-parse-stringify2 vulnerable to Regular expression denial of service (ReDoS)

Exploitation

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

CVSS

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

EPSS

• CVE-2021-23346: 2.13% estimated exploitation activity in the next 30 days; percentile 81.98 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

This affects the package html-parse-stringify before 2.0.1; all versions of package html-parse-stringify2. Sending certain input could cause one of the regular expressions that is used for parsing to backtrack, freezing the process.

Published by the source

18 Mar 2021, 19:39 UTC

Last modified by the source

14 Jan 2025, 08:56 UTC

Source last checked

26 Oct 2026, 12:26 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-545q-3fg6-48m7

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-545q-3fg6-48m7

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# Patch Next advisory brief: CVE-2021-23346

Advisory: html-parse-stringify and html-parse-stringify2 vulnerable to Regular expression denial of service (ReDoS)
IDs: CVE-2021-23346, GHSA-545q-3fg6-48m7
Record: https://patchnext.com/advisories/cve-2021-23346 (revision 2, source checked 26 Oct 2026, 12:26 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Partial vendor fix; fixed versions by package: html-parse-stringify 2.0.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm html-parse-stringify: affected < 2.0.1; fixed in 2.0.1
- npm html-parse-stringify2: affected <= 2.0.1

## Suggested inspection (read-only)
- `npm ls html-parse-stringify --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.
- `npm ls html-parse-stringify2 --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on html-parse-stringify, html-parse-stringify2.
- 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-545q-3fg6-48m7 (OSV record GHSA-545q-3fg6-48m7 lists affected ranges: npm html-parse-stringify >=0 =0 <=2.0.1)
- Verified: https://github.com/advisories/GHSA-545q-3fg6-48m7 (GitHub-reviewed advisory GHSA-545q-3fg6-48m7 lists affected ranges: npm html-parse-stringify >=0 =0 <=2.0.1)

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