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
- Exploited in the wild
- Not known
- Fix
- Available
What is CVE-2026-114129?
CVE-2026-114129 is a medium-severity vulnerability in uhop stream-json, published on 21 Oct 2026.
Official 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.
Weakness: CWE-407
Which versions are affected by CVE-2026-114129?
2 open source packages ship an affected version, including stream-json.
| Package | Affected | Fixed in |
|---|---|---|
stream-json npm | From 2.0.0 | 3.7.0 |
stream-json npm | From 2.0.0 | 3.7.0 |
How do I fix CVE-2026-114129?
Upgrade stream-json to 3.7.0 or later.
Is CVE-2026-114129 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-114129 exists.
Sources
Also known as GHSA-jj87-hc4r-jwfw.