stream-json: pick/ignore/filter/replace filters are O(depth²) on nested input — small crafted JSON blocks the event loop for seconds→minutes (DoS)

Exploitation

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

CVSS

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

EPSS

• CVE-2026-71429: 0.16% estimated exploitation activity in the next 30 days; percentile 5.25 (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.

Description The path filters pick, ignore, filter, and replace — the library's headline "surgical extraction" feature — recompute the full path string from the nesting stack on every checkable token. Because the stack length equals the current nesting depth, and a checkable token is emitted at every level, processing a document of depth D costs O(D²), not O(D). This is triggered by document structure (nesting depth), not byte volume, so a tiny payload achieves outsized CPU cost, and it is the ordinary "traverse until the filter matches" path — including the exact README flagship example pick({filter: 'data'}). Any service that uses these filters to extract a field from an untrusted (or larger-than-memory) JSON body — the primary documented use case — can be made to block its event loop. Affected code (v3.4.0) src/core/filters/filter-base.js: stack is pushed/popped on startObject/startArray/end (L239-250), so stack.length === depth. For a depth-D document that hasn't matched yet,…

Published by the source

3 Sep 2026, 20:27 UTC

Last modified by the source

3 Sep 2026, 20:27 UTC

Source last checked

26 Oct 2026, 13:02 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-528h-pc64-c93x

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# Patch Next advisory brief: CVE-2026-71429

Advisory: stream-json: pick/ignore/filter/replace filters are O(depth²) on nested input — small crafted JSON blocks the event loop for seconds→minutes (DoS)
IDs: CVE-2026-71429, GHSA-528h-pc64-c93x
Record: https://patchnext.com/advisories/cve-2026-71429 (revision 1, source checked 26 Oct 2026, 13:02 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.2)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: stream-json 3.5.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm stream-json: affected <= 3.4.0; fixed in 3.5.0

## Suggested inspection (read-only)
- `npm ls stream-json --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 stream-json.
- 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://github.com/advisories/GHSA-528h-pc64-c93x (GitHub-reviewed advisory GHSA-528h-pc64-c93x lists affected ranges: npm stream-json >=0 <=3.4.0)

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