CVE-2026-114129: stream-json: FlexAssembler string/RegExp path filters join the full key stack per container start, giving O(depth^2) CPU denial of service

Vulnerability summary

CVE-2026-114129 is a medium (CVSS 6.2) Inefficient Algorithmic Complexity vulnerability in uhop stream-json. EPSS estimates a 0.25% chance of exploitation in the next 30 days, higher than 17.1% of scored vulnerabilities.

Timeline

1. 21-10-2026
   PublishedVulnerability first disclosed.
2. 28-10-2026
   Last modifiedVulnerability information updated.

Description

stream-json is a micro-library of stream components for processing JSON and JSONC with a minimal memory footprint. From 2.0.0 until 3.7.0, FlexAssembler compiles string and regular-expression path filters into matchers that join the full key stack on every container start. Because the key stack grows with unbounded object or array nesting, a document nested to depth D causes D joins whose cost grows with the current depth, resulting in quadratic CPU consumption on the single-threaded event loop. The join occurs before the rule match decision, so the attacker does not need to know the target schema. Consumers using only function filters or no rules are not affected. A crafted nested document can stall all concurrent work in a process that feeds it to an affected FlexAssembler. This issue is fixed in 3.7.0, which adds a default maximum depth.

• CWE-407Inefficient Algorithmic ComplexityAn 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.