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@renovate renovate bot commented Feb 9, 2026

This PR contains the following updates:

Package Change Age Confidence
axios (source) 1.13.41.13.5 age confidence

GitHub Vulnerability Alerts

CVE-2026-25639

Denial of Service via proto Key in mergeConfig

Summary

The mergeConfig function in axios crashes with a TypeError when processing configuration objects containing __proto__ as an own property. An attacker can trigger this by providing a malicious configuration object created via JSON.parse(), causing complete denial of service.

Details

The vulnerability exists in lib/core/mergeConfig.js at lines 98-101:

utils.forEach(Object.keys({ ...config1, ...config2 }), function computeConfigValue(prop) {
  const merge = mergeMap[prop] || mergeDeepProperties;
  const configValue = merge(config1[prop], config2[prop], prop);
  (utils.isUndefined(configValue) && merge !== mergeDirectKeys) || (config[prop] = configValue);
});

When prop is '__proto__':

  1. JSON.parse('{"__proto__": {...}}') creates an object with __proto__ as an own enumerable property
  2. Object.keys() includes '__proto__' in the iteration
  3. mergeMap['__proto__'] performs prototype chain lookup, returning Object.prototype (truthy object)
  4. The expression mergeMap[prop] || mergeDeepProperties evaluates to Object.prototype
  5. Object.prototype(...) throws TypeError: merge is not a function

The mergeConfig function is called by:

  • Axios._request() at lib/core/Axios.js:75
  • Axios.getUri() at lib/core/Axios.js:201
  • All HTTP method shortcuts (get, post, etc.) at lib/core/Axios.js:211,224

PoC

import axios from "axios";

const maliciousConfig = JSON.parse('{"__proto__": {"x": 1}}');
await axios.get("https://httpbin.org/get", maliciousConfig);

Reproduction steps:

  1. Clone axios repository or npm install axios
  2. Create file poc.mjs with the code above
  3. Run: node poc.mjs
  4. Observe the TypeError crash

Verified output (axios 1.13.4):

TypeError: merge is not a function
    at computeConfigValue (lib/core/mergeConfig.js:100:25)
    at Object.forEach (lib/utils.js:280:10)
    at mergeConfig (lib/core/mergeConfig.js:98:9)

Control tests performed:

Test Config Result
Normal config {"timeout": 5000} SUCCESS
Malicious config JSON.parse('{"__proto__": {"x": 1}}') CRASH
Nested object {"headers": {"X-Test": "value"}} SUCCESS

Attack scenario:
An application that accepts user input, parses it with JSON.parse(), and passes it to axios configuration will crash when receiving the payload {"__proto__": {"x": 1}}.

Impact

Denial of Service - Any application using axios that processes user-controlled JSON and passes it to axios configuration methods is vulnerable. The application will crash when processing the malicious payload.

Affected environments:

  • Node.js servers using axios for HTTP requests
  • Any backend that passes parsed JSON to axios configuration

This is NOT prototype pollution - the application crashes before any assignment occurs.


Release Notes

axios/axios (axios)

v1.13.5

Compare Source

Release 1.13.5

Highlights
  • Security: Fixed a potential Denial of Service issue involving the __proto__ key in mergeConfig. (PR #​7369)
  • Bug fix: Resolved an issue where AxiosError could be missing the status field on and after v1.13.3. (PR #​7368)
Changes
Security
  • Fix Denial of Service via __proto__ key in mergeConfig. (PR #​7369)
Fixes
  • Fix/5657. (PR #​7313)
  • Ensure status is present in AxiosError on and after v1.13.3. (PR #​7368)
Features / Improvements
  • Add input validation to isAbsoluteURL. (PR #​7326)
  • Refactor: bump minor package versions. (PR #​7356)
Documentation
  • Clarify object-check comment. (PR #​7323)
  • Fix deprecated Buffer constructor usage and README formatting. (PR #​7371)
CI / Maintenance
  • Chore: fix issues with YAML. (PR #​7355)
  • CI: update workflow YAMLs. (PR #​7372)
  • CI: fix run condition. (PR #​7373)
  • Dev deps: bump karma-sourcemap-loader from 0.3.8 to 0.4.0. (PR #​7360)
  • Chore(release): prepare release 1.13.5. (PR #​7379)
New Contributors

Full Changelog: axios/axios@v1.13.4...v1.13.5


Configuration

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This PR was generated by Mend Renovate. View the repository job log.

@renovate renovate bot requested a review from a team as a code owner February 9, 2026 21:35
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github-actions bot commented Feb 9, 2026

NPM Publishing labels 🏷️

🔵 This PR has the none label set and it will not cause a version bump.

@dskloetc dskloetc added the none label Feb 10, 2026
@renovate renovate bot force-pushed the renovate/npm-axios-vulnerability branch from 3698d82 to 8483f71 Compare February 10, 2026 06:53
@renovate renovate bot force-pushed the renovate/npm-axios-vulnerability branch from 8483f71 to 6a1edc2 Compare February 10, 2026 06:57
@dskloetc dskloetc merged commit 72e9e51 into main Feb 10, 2026
14 checks passed
@renovate renovate bot deleted the renovate/npm-axios-vulnerability branch February 10, 2026 07:07
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🚀 Successfully created version bump PR: #686

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