LiquidJS Vulnerable to ReDoS via Quadratic Backtracking in strip_html Filter Regex

Exploitation

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

CVSS

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

EPSS

• CVE-2026-45617: 0.46% estimated exploitation activity in the next 30 days; percentile 39.77 (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.

Summary The built-in striphtml filter in liquidjs uses a regex containing four lazy-quantified alternatives. When the input contains many <script, <style, or <!-- opener tokens without matching closers, the V8 regex engine performs O(N²) backtracking, blocking the Node.js event loop. A single ~350 KB request ('<script'.repeat(50000)) stalls the process for ~10 seconds; cost grows quadratically with input size. The default memoryLimit: Infinity does not bound regex CPU, and even when configured striphtml only charges str.length to the limit — the regex itself runs unbounded. Details The vulnerable filter is at src/filters/html.ts:45-49: The regex contains four lazy patterns: 1. <script[\s\S]?<\/script 2. <style[\s\S]?<\/style 3. <.? 4. <!--[\s\S]?-- For an input like '<script'.repeat(N), the engine encounters N starting < positions. At each one it must lazily expand [\s\S]? (and .?) all the way to end-of-input searching for a closer that never appears, then fail and backtrack. Because…

Published by the source

27 May 2026, 18:08 UTC

Last modified by the source

10 Sep 2026, 03:50 UTC

Source last checked

26 Oct 2026, 12:56 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-r7g9-xpmj-5fcq

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-r7g9-xpmj-5fcq

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# Patch Next advisory brief: CVE-2026-45617

Advisory: LiquidJS Vulnerable to ReDoS via Quadratic Backtracking in `strip_html` Filter Regex
IDs: CVE-2026-45617, GHSA-r7g9-xpmj-5fcq
Record: https://patchnext.com/advisories/cve-2026-45617 (revision 2, 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: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: liquidjs 10.26.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm liquidjs: affected < 10.26.0; fixed in 10.26.0

## Suggested inspection (read-only)
- `npm ls liquidjs --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 liquidjs.
- 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-r7g9-xpmj-5fcq (OSV record GHSA-r7g9-xpmj-5fcq lists affected ranges: npm liquidjs >=0 <10.26.0 (fixed))
- Verified: https://github.com/advisories/GHSA-r7g9-xpmj-5fcq (GitHub-reviewed advisory GHSA-r7g9-xpmj-5fcq lists affected ranges: npm liquidjs >=0 <10.26.0)

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