CVE-2026-18540

{"id": "CVE-2026-18540", "cveTags": [], "metrics": {"ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-18540", "role": "CISA Coordinator", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "partial"}], "version": "2.0.3", "timestamp": "2026-09-04T17:50:05.851866Z"}}], "cvssMetricV31": [{"type": "Secondary", "source": "ce714d77-add3-4f53-aff5-83d477b104bb", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 3.7, "attackVector": "NETWORK", "baseSeverity": "LOW", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N", "integrityImpact": "LOW", "userInteraction": "NONE", "attackComplexity": "HIGH", "availabilityImpact": "NONE", "privilegesRequired": "NONE", "confidentialityImpact": "NONE"}, "impactScore": 1.4, "exploitabilityScore": 2.2}]}, "affected": [{"source": "ce714d77-add3-4f53-aff5-83d477b104bb", "affectedData": [{"vendor": "undici", "product": "undici", "versions": [{"status": "affected", "version": "0", "lessThan": "6.28.1", "versionType": "semver"}, {"status": "unaffected", "version": "6.28.1", "versionType": "semver"}, {"status": "affected", "version": "7.0.0", "lessThan": "7.29.1", "versionType": "semver"}, {"status": "unaffected", "version": "7.29.1", "versionType": "semver"}, {"status": "affected", "version": "8.0.0", "lessThan": "8.10.2", "versionType": "semver"}, {"status": "unaffected", "version": "8.10.2", "versionType": "semver"}], "packageURL": "pkg:npm/undici", "defaultStatus": "unaffected"}]}], "published": "2026-09-04T18:17:50.020", "references": [{"url": "https://cna.openjsf.org/security-advisories.html", "tags": ["Vendor Advisory"], "source": "ce714d77-add3-4f53-aff5-83d477b104bb"}, {"url": "https://github.com/nodejs/undici/security/advisories/GHSA-r53p-7pc4-xj5r", "tags": ["Mitigation", "Vendor Advisory"], "source": "ce714d77-add3-4f53-aff5-83d477b104bb"}], "vulnStatus": "Analyzed", "weaknesses": [{"type": "Secondary", "source": "ce714d77-add3-4f53-aff5-83d477b104bb", "description": [{"lang": "en", "value": "CWE-444"}]}], "descriptions": [{"lang": "en", "value": "undici's retry interceptor can append the body of a ranged retry response to bytes already delivered from an earlier partial response while still presenting the original response's status and headers. This happens when an upstream server delivers part of a body without a trustworthy resume checkpoint, for example a non-success response whose headers were already sent or a partial-content response with an unusable content range, then closes the connection and answers the resumed range request with more bytes. As a result the response body can be longer than the Content-Length that the application observes. An application that relays such a response to a downstream HTTP/1.1 peer without normalizing the framing can emit a body that exceeds the forwarded Content-Length, and the excess bytes can be interpreted as the start of a following response, which enables downstream response splitting or desynchronization. Exploitation requires an attacker-controlled upstream server and an application that forwards the response through a framing-sensitive path. This affects undici versions before 6.28.1, from 7.0.0 up to 7.29.1, and from 8.0.0 up to 8.10.2. Users should upgrade to undici 6.28.1, 7.29.1, or 8.10.2."}], "lastModified": "2026-09-16T20:41:17.627", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:nodejs:undici:*:*:*:*:*:node.js:*:*", "vulnerable": true, "matchCriteriaId": "6BF53143-07A7-4006-AC55-66FC8039FF5C", "versionEndExcluding": "6.28.1"}, {"criteria": "cpe:2.3:a:nodejs:undici:*:*:*:*:*:node.js:*:*", "vulnerable": true, "matchCriteriaId": "F51DCEB6-C60F-490F-AC91-1C6617CE7716", "versionEndExcluding": "7.29.1", "versionStartIncluding": "7.0.0"}, {"criteria": "cpe:2.3:a:nodejs:undici:*:*:*:*:*:node.js:*:*", "vulnerable": true, "matchCriteriaId": "848B6624-1708-4BF8-B9D7-8F34343D244B", "versionEndExcluding": "8.10.2", "versionStartIncluding": "8.0.0"}], "operator": "OR"}]}], "sourceIdentifier": "ce714d77-add3-4f53-aff5-83d477b104bb"}