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CVE-2026-25639 high CVSS 7.5

Vulnerability in axios (CVE-2026-25639)

Summary

Vulnerability in axios (CVE-2026-25639). Risk of unauthorized operations or information disclosure. Exploitable via mergeConfig. Mitigation: upgrade to 0.30.3 or later.

Original description

The description as published by the source.

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…

Source: GitHub Security Advisories (Global) NVD GitHub Advisory

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2026-25639 has been found in axios.
Attackers can target a specific entry point like mergeConfig over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 7.5/10.
What to do: upgrade axios to 0.30.3 or later.
If unsure, ask your IT team or search "axios CVE-2026-25639" on the vendor's site.

CVE-2026-25639 (axios) — CWE-754 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: mergeConfig / __proto__ / prop / Object.prototype
Patched: 0.30.3 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

A vulnerability (CWE-754) exists in axios. Attackers reach the vulnerable code path via mergeConfig without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of axios. Attack surface: mergeConfig / __proto__ / prop / Object.prototype.

🔥 Severity

Severity: High (CVSS 7.5/10). Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to 0.30.3.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'axios' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

  1. 1
    Identify exposure identify 
    grep -r 'axios' . | grep -v node_modules

    リポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で axios を grep し、稼働しているサービス・バージョンを把握する。

  2. 2
    Apply patch patch 
    Upgrade axios to 0.30.3

    ステージング環境で 0.30.3 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。

  3. 3
    Post-deployment verification verify 
    Confirm patched version is live in production

    パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

Affected packages

npm axios
[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"0.30.3"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

References

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