CVE-2026-42036 — axios
MEDIUMCVE-2026-42036 is a medium-severity (CVSS 5.3) CWE-770 vulnerability in axios. A fix is available for axios — see the affected versions and patch details below.
Axios: HTTP adapter streamed responses bypass maxContentLength
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-42036.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2026-42036 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,333 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
axiosnpmDescription
Summary
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:
- Start an HTTP server that returns a 2 MiB response body.
- Call Axios with:
- adapter: 'http'
- responseType: 'stream'
- maxContentLength: 1024
- 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.
Impact
Type: DoS / unbounded response processing. Impacted: Node.js applications relying on maxContentLength as a safety boundary while using streamed Axios responses.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | axios | ≥ 1.0.0&&< 1.15.1 | 1.15.1npm install axios@1.15.1 |
| 📦npm | axios | all versions | 0.31.1npm install axios@0.31.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for axios, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update axios to 1.15.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-42036 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-42036 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-42036. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-42036 in your dependencies?
O3 Security finds CVE-2026-42036 across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.