CVE-2026-42036

When responseType: 'stream' is used, Axios returns the response stream without enforcing maxContentLength. This bypasses configured response-size limits and allows unbounded downstream consumption.

Details

In lib/adapters/http.js:

• 786-789: for responseType === 'stream', Axios immediately settles with the stream.
• 797-810: maxContentLength enforcement exists only in the non-stream buffering branch.

So callers may set maxContentLength and still receive/read arbitrarily large streamed responses.

PoC

Environment:

• Axios main at commit f7a4ee2
• Node v24.2.0

Steps:

1. Start an HTTP server that returns a 2 MiB response body.
2. Call Axios with:
   • adapter: 'http'
   • responseType: 'stream'
   • maxContentLength: 1024
3. Read the returned stream fully.

Observed:

• Success; full 2097152 bytes readable.

Control check:

• Same endpoint with responseType: 'text' and same maxContentLength: rejected with maxContentLength size of 1024 exceeded.

Type: DoS / unbounded response processing.
Impacted: Node.js applications relying on maxContentLength as a safety boundary while using streamed Axios responses.

The application allocates resources such as memory, threads, or file descriptors based on untrusted input without enforcing a cap. Typical impact: resource exhaustion leading to denial of service.

CVE-2026-42036 has a CVSS score of 5.3 (Medium). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.15.1, 0.31.1); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2026-42036? CVE-2026-42036 is a medium-severity allocation of resources without limits or throttling vulnerability in axios (npm), affecting versions >= 1.0.0, < 1.15.1. It is fixed in 1.15.1, 0.31.1. The application allocates resources such as memory, threads, or file descriptors based on untrusted input without enforcing a cap.
2. How severe is CVE-2026-42036? CVE-2026-42036 has a CVSS score of 5.3 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of axios are affected by CVE-2026-42036? axios (npm) versions >= 1.0.0, < 1.15.1 is affected.
4. Is there a fix for CVE-2026-42036? Yes. CVE-2026-42036 is fixed in 1.15.1, 0.31.1. Upgrade to this version or later.
5. Is CVE-2026-42036 exploitable, and should I be worried? Whether CVE-2026-42036 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-42036 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-42036?
   • Upgrade axios to 1.15.1 or later
   • Upgrade axios to 0.31.1 or later