| Package | Affected versions | Patched versions |
|---|---|---|
| axios | ≥ 1.7.0, < 1.16.0 | 1.16.0 |
| axios | ≥ 1.7.0, < 1.16.0 | 1.16.0 |
Axios versions 1.7.0 through 1.15.x did not enforce configured request and response size limits when requests were sent with the fetch adapter. Applications that selected adapter: 'fetch', or ran in environments where axios resolved to the fetch adapter, could receive or send bodies larger than maxContentLength or maxBodyLength despite those limits being explicitly configured.
This can cause resource exhaustion in server-side usage when a malicious or compromised server returns an oversized response, when an attacker can supply a large data: URL, or when an application forwards attacker-controlled request bodies through axios while relying on maxBodyLength as a boundary.
The impact is availability-only. Affected applications may process, buffer, or transmit data beyond the configured limit, potentially exhausting memory, CPU, or network resources.
This does not affect axios’s default unlimited behaviour by itself: maxContentLength and maxBodyLength default to -1. The vulnerability exists when an application has configured finite limits and expects axios to enforce them.
Server-side runtimes are the primary concern. Browser impact is generally constrained by the browser process and browser fetch behavior, and should not be described as server process exhaustion.
Affected functionality includes requests using the built-in fetch adapter with finite maxContentLength or maxBodyLength values.
Relevant configurations include:
adapter: 'fetch'adapter: ['fetch', ...] when fetch is selectedxhr nor http is available and axios falls back to fetchenv.fetchUnaffected functionality includes:
http adapter enforcementIn vulnerable versions, lib/adapters/fetch.js destructured request config without maxContentLength or maxBodyLength. The adapter dispatched and then materialized the response through , , , or related resolvers without checking the configured response limit.
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Scan my site freefetch()text()arrayBuffer()blob()The fix in e5540dc added:
maxContentLength and maxBodyLength reads in lib/adapters/fetch.jsdata: URL decoded-size checksContent-Length response pre-checksReadableStreamtests/unit/adapters/fetch.test.jsimport http from 'node:http';
import axios from 'axios';
const server = http.createServer((req, res) => {
let received = 0;
req.on('data', chunk => {
received += chunk.length;
});
req.on('end', () => {
res.end(JSON.stringify({ received }));
});
});
await new Promise(resolve => server.listen(0, resolve));
const url = `http://127.0.0.1:${server.address().port}/`;
await axios.post(url, 'A'.repeat(2 * 1024 * 1024), {
adapter: 'fetch',
maxBodyLength: 1024
});
// Vulnerable versions succeed and the server receives 2097152 bytes.
// Fixed versions reject with ERR_BAD_REQUEST.
server.close();
Use the Node.js http adapter for server-side requests where finite size limits are security-relevant.
Validate or cap attacker-controlled request bodies before passing them to axios.
Reject or strictly allowlist attacker-controlled URL schemes, especially data: URLs, before calling axios.
When Axios is used with adapter: 'fetch', configured body/response size limits are not enforced. This allows oversized uploads/downloads (including data: URLs) despite explicit limits, which can lead to memory/resource exhaustion in server-side usage.
maxBodyLength and maxContentLength are not applied in the fetch adapter flow:
Environment:
Steps:
Expected secure behavior: both requests rejected. Observed:
Type: DoS / resource exhaustion due to limit bypass. Impacted: applications using Axios fetch adapter as a server-side security control boundary for untrusted request/response sizes.