stream-json: JSONC parser and verifier re-scan the whole accumulated comment on every input chunk

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-2026-104182: 0.20% estimated exploitation activity in the next 30 days; percentile 10.24 (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 JSONC parser (stream-json/jsonc/parser.js) and verifier (stream-json/jsonc/verifier.js) scan a comment for its terminator starting from the comment's opening / on every input chunk. When a comment doesn't finish inside the current buffer, the scanner returns the comment's start offset and the buffer keeps the whole comment, so the next chunk re-scans everything seen so far. A single comment of length n delivered across many chunks costs O(n²) CPU. This is the same class as GHSA-528h-pc64-c93x (path filters, medium, CWE-407): an algorithmic-complexity re-scan in a streaming feature. It's a different code path though — the comment scanner in handleComment, which the 3.5.0 depth cap doesn't touch — so upgrading past that advisory doesn't help here. The plain JSON parser is fine: its strings and numbers advance and drop consumed bytes, and only comments retain and re-scan. Proof of concept Timing the pipeline (Node 22, one core, clean install): a 2 MB comment blocks the event…

Published by the source

5 Oct 2026, 22:49 UTC

Last modified by the source

5 Oct 2026, 23:00 UTC

Source last checked

26 Oct 2026, 13:06 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-hqr4-qq8f-hg3x

2. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GHSA-hqr4-qq8f-hg3x

3. Revision 1 · created · 23 Oct 2026

   Published from ghsa record GHSA-hqr4-qq8f-hg3x

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-104182

Advisory: stream-json: JSONC parser and verifier re-scan the whole accumulated comment on every input chunk
IDs: CVE-2026-104182, GHSA-hqr4-qq8f-hg3x
Record: https://patchnext.com/advisories/cve-2026-104182 (revision 3, source checked 26 Oct 2026, 13:06 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 3.6.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm stream-json: affected <= 3.5.0; fixed in 3.6.0

## 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-hqr4-qq8f-hg3x (GitHub-reviewed advisory GHSA-hqr4-qq8f-hg3x lists affected ranges: npm stream-json >=0 <=3.5.0)
- Verified: https://osv.dev/vulnerability/GHSA-hqr4-qq8f-hg3x (OSV record GHSA-hqr4-qq8f-hg3x lists affected ranges: npm stream-json >=0 <3.6.0 (fixed))

Commands are suggestions: review each one before running it.