What is CVE-2026-40175?

CVE-2026-40175 is a security vulnerability identified in axios. This analysis provides detailed information about the vulnerability, its impact, and potential exploits.

Is there a PoC for CVE-2026-40175?

This security analysis examines the vulnerability in detail. Review the analysis findings for exploit potential and proof-of-concept information related to CVE-2026-40175.

How can I protect against CVE-2026-40175?

Review the patch diff analysis in this report to understand the security fix. Updating to the patched version is recommended to mitigate CVE-2026-40175.

REPORT / 01

Analysis Report · axios v1.14.0 → v1.15.0 — CVE-2026-40175

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Comprehensive security analysis generated by AI for each confirmed CVE match. Click on a CVE to view the detailed writeup including vulnerability background, technical details, patch analysis, and PoC guide.

CVE-2026-40175 NVD

AI-Generated Analysis

## 1. Vulnerability Background

CVE-2026-40175 is a high-impact vulnerability affecting Axios versions prior to 1.15.0 and 0.3.1. Axios is a widely used promise-based HTTP client for browsers and Node.js, and this issue is notable because it allows a prototype pollution condition in any third-party dependency to be escalated through Axios into far more severe outcomes.

Why it is critical:
- Prototype pollution is a dangerous class of JavaScript vulnerability because it changes the behavior of otherwise benign object operations.
- In this case, the vulnerability is part of a gadget chain that can turn prototype pollution into remote code execution (RCE).
- The exploit path also includes the possibility of full cloud compromise via AWS IMDSv2 bypass, making it especially dangerous for cloud-hosted Node.js applications.

Affected systems/versions:
- Axios versions older than 1.15.0
- Axios legacy branch versions older than 0.3.1
- Both browser and Node.js applications that depend on these versions, especially when combined with a third-party dependency already vulnerable to prototype pollution

## 2. Technical Details

Root cause analysis:
- The patch diff shows two distinct unsafe patterns in `docs/scripts/process-sponsors.js`:
  1. `buildLinks` accepted arbitrary URLs and normalized them without validating the URL scheme.
  2. `sponsorsByTier` was initialized as a normal object literal (`{}`) and populated using attacker-controlled keys derived from `sponsor.tier`.

- The first flaw means `new URL(url)` could process `javascript:`, `data:`, or other non-HTTP schemes and then return a normalized value. In contexts where this value is later used in HTML or as a redirect target, it can lead to unsafe behavior.
- The second flaw is classic prototype pollution territory. When dynamic keys are indexed into a plain object, keys like `__proto__`, `constructor`, or inherited property names can collide with the object prototype. This can lead to unexpected property resolution and can be used as part of a gadget chain to poison object behavior.

Attack vector and exploitation conditions:
- An attacker needs a way to influence the inputs processed by Axios or the surrounding application logic.
- In the sample patched code, the attacker-controlled data would be:
  - a sponsor URL passed to `buildLinks`
  - a sponsor tier value used as an object key in `sponsorsByTier`
- The real-world escalation relies on a third-party dependency already allowing prototype pollution; Axios’s unsafe handling makes that pollution exploitable in a higher-impact way.

Security implications:
- If a vulnerable application uses Axios in a code path that processes untrusted data, an attacker can potentially escalate a prototype pollution bug into RCE.
- In cloud deployments, compromise can go further by abusing the gadget chain to bypass AWS IMDSv2 protections and retrieve instance credentials.

## 3. Patch Analysis

What code changes were made:
- In `buildLinks`, the patched code adds a protocol allowlist:
  - only `http:` and `https:` are accepted after parsing the URL
  - any other protocol causes the function to return `null`
- The catch block was also hardened to return `null` instead of the original URL.
- In sponsor aggregation logic, `sponsorsByTier` initialization changed from:
  - `const sponsorsByTier = {};`
  to:
  - `const sponsorsByTier = Object.create(null);`

How these changes fix the vulnerability:
- URL scheme validation prevents attacker-supplied non-HTTP URLs from being treated as safe output. This closes an injection/redirect/unsafe URL path that could otherwise be used in exploitation.
- Using `Object.create(null)` removes the standard object prototype from `sponsorsByTier`. This means arbitrary keys are stored as pure data and cannot collide with inherited prototype properties such as `__proto__`, `constructor`, `toString`, etc.

Security improvements introduced:
- Failing closed on invalid or unsafe URL inputs.
- Removal of prototype inheritance from an object used as a dynamic key map.
- Elimination of a class of prototype pollution vectors from the affected code path.

## 4. Proof of Concept (PoC) Guide

Prerequisites for exploitation:
- A vulnerable Axios build or environment using Axios <1.15.0 / <0.3.1
- Control over data that reaches the vulnerable processing code, specifically:
  - sponsor URLs
  - sponsor tier strings

Step-by-step exploitation approach:
1. Prototype pollution vector:
   - Supply a sponsor entry with a tier value such as `__proto__`, `constructor`, or `toString`.
   - Let the code process `sponsorsByTier[sponsor.tier] ||= []` on a plain object.
   - Because `sponsorsByTier` inherits from `Object.prototype`, this can interact badly with prototype properties and allow unexpected behavior.

2. URL scheme vector:
   - Supply a sponsor URL like `javascript:alert(1)` or `data:text/plain,hello`.
   - The vulnerable `buildLinks` function will accept it, create a URL object, append UTM parameters, and return the normalized string.
   - The result is an unsafe URL that may be reflected or used in the application.

Expected behavior vs exploited behavior:
- Expected:
  - Only `http` and `https` links are accepted and rewritten.
  - Sponsor tier keys are stored in a pure map without prototype consequences.
- Exploited:
  - Non-http schemes are accepted, allowing dangerous URLs to be emitted.
  - Special tier keys can collide with the prototype, leading to prototype pollution or broken application logic.

How to verify the vulnerability exists:
- For URL validation:
  - Run `buildLinks('javascript:alert(1)')` against the vulnerable code.
  - If it returns a string starting with `javascript:`, the unsafe behavior is present.
  - After patch, it should return `null`.

- For prototype pollution:
  - Run the sponsor aggregation with a tier value like `__proto__` or `toString`.
  - If the code uses a normal object, the behavior will differ from a prototype-less map and may fail to create the intended bucket or may expose inheritance collisions.
  - After patch, `Object.create(null)` ensures such keys are handled safely as plain data.

## 5. Recommendations

Mitigation strategies:
- Upgrade Axios to at least 1.15.0 or 0.3.1.
- If immediate upgrade is not possible, audit application code for untrusted URL handling and dynamic object property assignment.
- Treat user-controlled strings used as object keys as untrusted input and avoid mapping them into plain objects with inherited prototypes.

Detection methods:
- Scan dependencies for axios versions <1.15.0 / <0.3.1.
- Static code analysis for:
  - `new URL(...)` used without validating the protocol
  - dynamic object keys on object literals (`{}`) when the key originates from external input
- Runtime tests that exercise malicious values such as `javascript:` URLs and prototype property names.

Best practices to prevent similar issues:
- Use allowlists for URL schemes and reject anything outside `http`/`https` in contexts where only web URLs are expected.
- Use `Object.create(null)` or `Map` for dynamic maps keyed by untrusted values.
- Avoid `||=` or similar assignment patterns on objects that may have inherited properties if keys are attacker-controlled.
- Harden JavaScript code against prototype pollution by validating and canonicalizing input at the boundary.
- Monitor the dependency chain for gadget-chain vulnerabilities, not just direct package issues, since prototype pollution often requires a multi-stage exploitation path.

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docs/scripts/process-sponsors.js AI: 2 vulnerabilities 2 true positive(s) CVE-2026-40175

--- /dev/null+++ cache/axios_v1.15.0/docs/scripts/process-sponsors.js@@ -0,0 +1,294 @@+import fs from 'node:fs';+import axios from 'axios';+import { printSuccessMessage, printErrorMessage, printInfoMessage } from './utils.js';++/**+ * Special configuration for processing sponsor data.+ */+const config = {+  legacyAgreements: {+    Stytch: 'gold',+    Airbnb: 'silver',+    Descope: 'gold',+    'Principal Financial Group': 'gold',+  },+  sponsorsToIgnore: ['axios'],+};++/**+ * The GraphQL query to get all sponsors.+ *+ * @type {string}+ */+const getAllSponsorsQuery = `+query Account {+  account(githubHandle: "https://github.com/axios") {+    name+    slug+    members(role: BACKER) {+      totalCount+      nodes {+        account {+          name+          slug+          socialLinks {+            type+            url+            createdAt+            updatedAt+          }+          website+          imageUrl+          legalName+          description+        }+        tier {+          name+        }+        totalDonations {+          value+          currency+        }+        since+      }+    }+  }+}+`;++/**+ * The GraphQL query to get all active sponsors.+ *+ * @type {string}+ */+const getActiveSponsorsQuery = `+query Account {+  account(githubHandle: "https://github.com/axios") {+    orders(onlyActiveSubscriptions: true, onlySubscriptions: true, frequency: MONTHLY, status: ACTIVE) {+      totalCount+      nodes {+        tier {+          name+        }+        fromAccount {+          id+          name+          socialLinks {+            type+            url+          }+          imageUrl+          legalName+          description+          website+          slug+        }+        amount {+          currency+          value+        }+        totalDonations {+          value+          currency+        }+      }+    }+  }+}+`;++/**+ * Gets all sponsors.+ *+ * @returns {Promise<any>} The sponsors.+ */+const getAllSponsors = async () => {+  printInfoMessage('getting all sponsors...');+  const response = await axios.post('https://api.opencollective.com/graphql/v2', {+    query: getAllSponsorsQuery,+  });++  return response.data.data;+};++/**+ * Gets all active sponsors.+ *+ * @returns {Promise<any>} The active sponsors.+ */+const getActiveSponsors = async () => {+  printInfoMessage('getting active sponsors...');+  const response = await axios.post('https://api.opencollective.com/graphql/v2', {+    query: getActiveSponsorsQuery,+  });++  return response.data.data;+};++/**+ * Builds a URL with UTM parameters.+ *+ * @param {string} url - The URL to build.+ * @param {boolean} bypass - Whether to bypass UTM parameters.+ * @returns {string} The URL with UTM parameters.+ */+const buildLinks = (url, bypass = false) => {+  if (bypass) {+    return url;+  }++  try {+    const urlObject = new URL(url);++    const { searchParams } = urlObject;++    searchParams.set('utm_source', 'axios_docs_website');+    searchParams.set('utm_medium', 'website');+    searchParams.set('utm_campaign', 'axios_open_collective_sponsorship');++    return urlObject.toString();+  } catch {+    return url;+  }+};++/**+ * Formats all active sponsors.+ *+ * @param {any} sponsorsData - The sponsors data.+ * @returns {any} The formatted sponsor data.+ */+const formatActiveSponsorData = (sponsorsData) => {+  const getSponsorTier = (sponsor) => {+    if (config.legacyAgreements[sponsor.fromAccount.name]) {+      return config.legacyAgreements[sponsor.fromAccount.name];+    }++    if (sponsor.tier?.name.toLowerCase() === 'silver sponsor') {+      return 'silver';+    }++    return sponsor.tier?.name.toLowerCase() || 'backer';+  };++  const processedData = sponsorsData+    .map((sponsor) => ({+      name: sponsor.fromAccount.name ?? 'Backer',+      imageUrl: sponsor.fromAccount.imageUrl ?? null,+      description: sponsor.fromAccount.description ?? null,+      tier: getSponsorTier(sponsor),+      slug: sponsor.fromAccount.slug,+      website: sponsor.fromAccount.website+        ? buildLinks(sponsor.fromAccount.website)+        : (buildLinks(+            sponsor.fromAccount.socialLinks.find((link) => link.type === 'WEBSITE')?.url+          ) ?? null),+      twitter:+        buildLinks(sponsor.fromAccount.socialLinks.find((link) => link.type === 'TWITTER')?.url) ??+        null,+    }))+    .filter((sponsor) => !config.sponsorsToIgnore.includes(sponsor.name));++  return processedData;+};++/**+ * Formats all sponsors irrespective state.+ *+ * @param {any} sponsorsData - The sponsors data.+ * @returns {any} The formatted sponsor data.+ */+const formatAllSponsorData = (sponsorsData) => {+  const getSponsorTier = (sponsor) => {+    if (config.legacyAgreements[sponsor.account.name]) {+      return config.legacyAgreements[sponsor.account.name];+    }++    if (sponsor.tier?.name.toLowerCase() === 'silver sponsor') {+      return 'silver';+    }++    return sponsor.tier?.name.toLowerCase() || 'backer';+  };++  const processedData = sponsorsData+    .map((sponsor) => ({+      name: sponsor.account.name ?? 'Backer',+      imageUrl: sponsor.account.imageUrl ?? null,+      description: sponsor.account.description ?? null,+      tier: getSponsorTier(sponsor),+      slug: sponsor.account.slug,+      website: sponsor.account.website+        ? buildLinks(sponsor.account.website)+        : (buildLinks(sponsor.account.socialLinks.find((link) => link.type === 'WEBSITE')?.url) ??+          null),+      twitter:+        buildLinks(sponsor.account.socialLinks.find((link) => link.type === 'TWITTER')?.url) ??+        null,+    }))+    .filter((sponsor) => !config.sponsorsToIgnore.includes(sponsor.name));++  return processedData;+};++/**+ * The main process.+ */+const mainProcess = async () => {+  try {+    const allSponsors = await getAllSponsors();+    const activeSponsors = await getActiveSponsors();+    const allSponsorsProcessedData = formatAllSponsorData(allSponsors.account.members.nodes);+    const activeSponsorsProcessedData = formatActiveSponsorData(+      activeSponsors.account.orders.nodes+    );++    const sponsorsByTier = {};++    for (const sponsor of allSponsorsProcessedData) {+      sponsorsByTier[sponsor.tier] ||= [];++      const isActiveSponsor = activeSponsorsProcessedData.find(+        (activeSponsor) => activeSponsor.slug === sponsor.slug+      );++      if (isActiveSponsor) {+        sponsorsByTier[sponsor.tier].push({+          ...sponsor,+          active: true,+        });+      } else {+        sponsorsByTier[sponsor.tier].push({+          ...sponsor,+          active: false,+        });+      }+    }++    for (const sponsor of activeSponsorsProcessedData) {+      const isSponsorInAllSponsors = allSponsorsProcessedData.find(+        (allSponsor) => allSponsor.slug === sponsor.slug+      );++      if (!isSponsorInAllSponsors) {+        if (!sponsorsByTier[sponsor.tier]) {+          sponsorsByTier[sponsor.tier] ||= [];+        }++        sponsorsByTier[sponsor.tier].push({+          ...sponsor,+          active: true,+        });+      }+    }++    fs.writeFileSync('./data/sponsors.json', JSON.stringify(sponsorsByTier, null, 2));++    printSuccessMessage('processed sponsors successfully!');+  } catch (_) {+    printErrorMessage('failed to process sponsors!');+    console.error(_);+  }+};++await mainProcess();

AI Analysis

Vulnerability Existed: yes
TRUE POSITIVE
Unvalidated URL Scheme [docs/scripts/process-sponsors.js] [135-153]
[Old Code]
const buildLinks = (url, bypass = false) => {
  if (bypass) {
    return url;
  }

  try {
    const urlObject = new URL(url);

    const { searchParams } = urlObject;

    searchParams.set('utm_source', 'axios_docs_website');
    searchParams.set('utm_medium', 'website');
    searchParams.set('utm_campaign', 'axios_open_collective_sponsorship');

    return urlObject.toString();
  } catch {
    return url;
  }
};
[Fixed Code]
const buildLinks = (url, bypass = false) => {
  if (bypass) {
    return url;
  }

  try {
    const urlObject = new URL(url);

    if (!['http:', 'https:'].includes(urlObject.protocol)) {
      return null;
    }

    const { searchParams } = urlObject;

    searchParams.set('utm_source', 'axios_docs_website');
    searchParams.set('utm_medium', 'website');
    searchParams.set('utm_campaign', 'axios_open_collective_sponsorship');

    return urlObject.toString();
  } catch {
    return null;
  }
};

Vulnerability Existed: yes
TRUE POSITIVE
Prototype Pollution via dynamic object keys [docs/scripts/process-sponsors.js] [263-292]
[Old Code]
    const sponsorsByTier = {};

    for (const sponsor of allSponsorsProcessedData) {
      sponsorsByTier[sponsor.tier] ||= [];

      const isActiveSponsor = activeSponsorsProcessedData.find(
        (activeSponsor) => activeSponsor.slug === sponsor.slug
      );

      ...
    }

    for (const sponsor of activeSponsorsProcessedData) {
      const isSponsorInAllSponsors = allSponsorsProcessedData.find(
        (allSponsor) => allSponsor.slug === sponsor.slug
      );

      if (!isSponsorInAllSponsors) {
        if (!sponsorsByTier[sponsor.tier]) {
          sponsorsByTier[sponsor.tier] ||= [];
        }

        sponsorsByTier[sponsor.tier].push({
          ...sponsor,
          active: true,
        });
      }
    }
[Fixed Code]
    const sponsorsByTier = Object.create(null);

    for (const sponsor of allSponsorsProcessedData) {
      sponsorsByTier[sponsor.tier] ||= [];

      const isActiveSponsor = activeSponsorsProcessedData.find(
        (activeSponsor) => activeSponsor.slug === sponsor.slug
      );

      ...
    }

    for (const sponsor of activeSponsorsProcessedData) {
      const isSponsorInAllSponsors = allSponsorsProcessedData.find(
        (allSponsor) => allSponsor.slug === sponsor.slug
      );

      if (!isSponsorInAllSponsors) {
        if (!sponsorsByTier[sponsor.tier]) {
          sponsorsByTier[sponsor.tier] ||= [];
        }

        sponsorsByTier[sponsor.tier].push({
          ...sponsor,
          active: true,
        });
      }
    }

CVE Analysis Results:

CVE-2026-40175: Yes

View CVE Description

Axios is a promise based HTTP client for the browser and Node.js. Prior to 1.15.0 and 0.3.1, the Axios library is vulnerable to a specific "Gadget" attack chain that allows Prototype Pollution in any third-party dependency to be escalated into Remote Code Execution (RCE) or Full Cloud Compromise (via AWS IMDSv2 bypass). This vulnerability is fixed in 1.15.0 and 0.3.1.

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