CVE-2026-42034 — axios
MEDIUMCVE-2026-42034 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 uploads bypass maxBodyLength when maxRedirects: 0
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-2026-42034.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
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
For stream request bodies, maxBodyLength is bypassed when maxRedirects is set to 0 (native http/https transport path). Oversized streamed uploads are sent fully even when the caller sets strict body limits.
Details
Relevant flow in lib/adapters/http.js:
- 556-564: maxBodyLength check applies only to buffered/non-stream data.
- 681-682: maxRedirects === 0 selects native http/https transport.
- 694-699: options.maxBodyLength is set, but native transport does not enforce it.
- 925-945: stream is piped directly to socket (data.pipe(req)) with no Axios byte counting.
This creates a path-specific bypass for streamed uploads.
PoC
Environment:
- Axios main at commit f7a4ee2
- Node v24.2.0
Steps:
- Start an HTTP server that counts uploaded bytes and returns {received}.
- Send a 2 MiB Readable stream with:
- adapter: 'http'
- maxBodyLength: 1024
- maxRedirects: 0
Observed:
- Request succeeds; server reports received: 2097152.
Control checks:
- Same stream with default/nonzero redirects: rejected with ERR_FR_MAX_BODY_LENGTH_EXCEEDED.
- Buffered body with maxRedirects: 0: rejected with ERR_BAD_REQUEST.
Impact
Type: DoS / uncontrolled upstream upload / resource exhaustion. Impacted: Node.js services using streamed request bodies with maxBodyLength expecting hard enforcement, especially when following Axios guidance to use maxRedirects: 0 for streams.
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 |
Affected Products
axiosaxiosDetection & 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-2026-42034 is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Ceph Storage 9.2 | rhceph/rhceph-9-rhel10:1790843527 | RHSA-2026:86618 |
Frequently Asked Questions
Is CVE-2026-42034 in your dependencies?
Find it across npm, including transitive dependencies.