CVE-2026-71429
Received Received - Intake

Path Traversal in stream-json via Deep Nesting

Vulnerability report for CVE-2026-71429, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.

Publication date: 2026-09-03

Last updated on: 2026-09-03

Assigner: GitHub, Inc.

Description

stream-json is a micro-library of stream components for processing JSON and JSONC with a minimal memory footprint. Prior to 3.5.0, the path filters pick, ignore, filter, and replace in src/core/filters/filter-base.js recompute the full path string from the nesting stack for every checkable token. Because the stack length equals the current nesting depth and a checkable token is emitted at every level, a depth D document costs O(DΒ²) rather than O(D) to process. The issue is triggered by nesting depth rather than byte volume, including the documented pick({filter: 'data'}) traversal-until-match path, so an application that sends untrusted JSON through a string or RegExp filter can block the Node.js event loop and cause denial of service with a small deeply nested document. The streamArray, streamObject, and streamValues streamers are not affected because they use the constant-time asm.depth getter. This issue is fixed in version 3.5.0.

CVSS Scores

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Meta Information

Published
2026-09-03
Last Modified
2026-09-03
Generated
2026-09-04
AI Q&A
2026-09-04
EPSS Evaluated
N/A
NVD

Affected Vendors & Products

Currently, no data is known.

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-407 An algorithm in a product has an inefficient worst-case computational complexity that may be detrimental to system performance and can be triggered by an attacker, typically using crafted manipulations that ensure that the worst case is being reached.

Attack-Flow Graph

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Executive Summary

This vulnerability is in the stream-json library before version 3.5.0. It involves path filters (pick, ignore, filter, replace) that recompute the full path string from the nesting stack for every token check. This leads to O(DΒ²) processing time for a document with depth D instead of the expected O(D), causing high CPU usage and potential denial of service with deeply nested JSON.

Detection Guidance

This vulnerability is specific to the stream-json library and is triggered by deeply nested JSON documents. Detection involves checking the version of stream-json in use and monitoring for high CPU usage or event loop delays when processing JSON data.

Impact Analysis

An attacker could send a small but deeply nested JSON document to an application using the affected stream-json library. This would cause the event loop to block, leading to high CPU usage and denial of service. Applications processing untrusted JSON with string or RegExp filters are particularly vulnerable.

Mitigation Strategies

Upgrade stream-json to version 3.5.0 or later to resolve the issue. If upgrading is not immediately possible, avoid using path filters like pick, ignore, filter, or replace on untrusted JSON input.

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