CVE-2026-104182 stream-json: JSONC parser and verifier re-scan the whole accumulated comment on every input chunk
An attacker can cause a denial of service by sending large JSONC comments in small chunks, triggering quadratic CPU usage in the stream-json library.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-104182?
CVE-2026-104182 is a medium-severity denial of service vulnerability in uhop stream-json, published on 1 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
stream-json is a micro-library of stream components for processing JSON and JSONC with a minimal memory footprint. Prior to 3.6.0, the JSONC parser at stream-json/jsonc/parser.js and verifier at stream-json/jsonc/verifier.js restart comment-terminator scanning from the opening slash whenever a block or line comment spans an input chunk, while retaining the accumulated comment buffer. Delivering a large valid comment across many small chunks therefore causes quadratic CPU work and can stall the Node.js event loop. The maintainer characterizes the attack vector as local because the documented JSONC input is locally owned or user-controlled configuration, rather than input intended for the open internet. This JSONC-only scope does not include the plain JSON parser, which advances through and discards consumed string and number data. This issue is fixed in version 3.6.0.
Weakness: CWE-407
Which versions are affected by CVE-2026-104182?
2 open source packages ship an affected version, including stream-json.
| Package | Affected | Fixed in |
|---|---|---|
stream-json npm | All versions | 3.6.0 |
stream-json npm | All versions | 3.6.0 |
How do I fix CVE-2026-104182?
Upgrade stream-json to 3.6.0 or later.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-104182 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-104182 exists.
Sources
Also known as CLEANSTART-2026-EJ44011, GHSA-hqr4-qq8f-hg3x.