{"api_version":"1","generated_at":"2026-11-04T05:40:54+00:00","cve":"CVE-2026-63476","urls":{"html":"https://cve.report/CVE-2026-63476","api":"https://cve.report/api/cve/CVE-2026-63476.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-63476","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-63476"},"summary":{"title":"isomorphic-git: Unbounded memory allocation from attacker-controlled delta target size (DoS)","description":"isomorphic-git is a pure JavaScript implementation of Git for Node.js and browsers. Prior to 1.38.6, isomorphic-git reads a server-controlled targetSize while applying a packfile delta in src/utils/applyDelta.js and passes it without a bound to Buffer.alloc(targetSize). A malicious or man-in-the-middle-controlled remote can send one delta header that causes git.clone() or git.fetch() to allocate approximately 2 GB before validating the actual delta output. GitPackIndex.fromPack swallows the later size-mismatch error, so a host with sufficient memory may retain the resource waste without a visible failure, while containers, serverless functions, and small virtual machines may terminate. Node.js heap limits do not mitigate the off-heap Buffer allocation. This issue is fixed in version 1.38.6.","state":"PUBLISHED","assigner":"GitHub_M","published_at":"2026-11-03 20:18:16","updated_at":"2026-11-03 20:18:16"},"problem_types":["CWE-400","CWE-789","CWE-400 CWE-400: Uncontrolled Resource Consumption","CWE-789 CWE-789: Memory Allocation with Excessive Size Value"],"metrics":[{"version":"3.1","source":"security-advisories@github.com","type":"Secondary","score":"4.3","severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L","baseScore":4.3,"baseSeverity":"MEDIUM","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"REQUIRED","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"LOW"}},{"version":"3.1","source":"CNA","type":"DECLARED","score":"4.3","severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L","data":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"LOW","baseScore":4.3,"baseSeverity":"MEDIUM","confidentialityImpact":"NONE","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"REQUIRED","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L","version":"3.1"}}],"references":[{"url":"https://github.com/isomorphic-git/isomorphic-git/pull/2370","name":"https://github.com/isomorphic-git/isomorphic-git/pull/2370","refsource":"security-advisories@github.com","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://github.com/isomorphic-git/isomorphic-git/releases/tag/v1.38.6","name":"https://github.com/isomorphic-git/isomorphic-git/releases/tag/v1.38.6","refsource":"security-advisories@github.com","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://github.com/isomorphic-git/isomorphic-git/security/advisories/GHSA-9x82-4j54-863h","name":"https://github.com/isomorphic-git/isomorphic-git/security/advisories/GHSA-9x82-4j54-863h","refsource":"security-advisories@github.com","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://github.com/isomorphic-git/isomorphic-git/commit/823843d1cd19182df79bc907c767f5bcecb39a0b","name":"https://github.com/isomorphic-git/isomorphic-git/commit/823843d1cd19182df79bc907c767f5bcecb39a0b","refsource":"security-advisories@github.com","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-63476","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-63476","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"isomorphic-git","product":"isomorphic-git","version":"affected < 1.38.6","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"product":"isomorphic-git","vendor":"isomorphic-git","versions":[{"status":"affected","version":"< 1.38.6"}]}],"descriptions":[{"lang":"en","value":"isomorphic-git is a pure JavaScript implementation of Git for Node.js and browsers. Prior to 1.38.6, isomorphic-git reads a server-controlled targetSize while applying a packfile delta in src/utils/applyDelta.js and passes it without a bound to Buffer.alloc(targetSize). A malicious or man-in-the-middle-controlled remote can send one delta header that causes git.clone() or git.fetch() to allocate approximately 2 GB before validating the actual delta output. GitPackIndex.fromPack swallows the later size-mismatch error, so a host with sufficient memory may retain the resource waste without a visible failure, while containers, serverless functions, and small virtual machines may terminate. Node.js heap limits do not mitigate the off-heap Buffer allocation. This issue is fixed in version 1.38.6."}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"LOW","baseScore":4.3,"baseSeverity":"MEDIUM","confidentialityImpact":"NONE","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"REQUIRED","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-400","description":"CWE-400: Uncontrolled Resource Consumption","lang":"en","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-789","description":"CWE-789: Memory Allocation with Excessive Size Value","lang":"en","type":"CWE"}]}],"providerMetadata":{"dateUpdated":"2026-11-03T19:44:06.908Z","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","shortName":"GitHub_M"},"references":[{"name":"https://github.com/isomorphic-git/isomorphic-git/security/advisories/GHSA-9x82-4j54-863h","tags":["x_refsource_CONFIRM"],"url":"https://github.com/isomorphic-git/isomorphic-git/security/advisories/GHSA-9x82-4j54-863h"},{"name":"https://github.com/isomorphic-git/isomorphic-git/pull/2370","tags":["x_refsource_MISC"],"url":"https://github.com/isomorphic-git/isomorphic-git/pull/2370"},{"name":"https://github.com/isomorphic-git/isomorphic-git/commit/823843d1cd19182df79bc907c767f5bcecb39a0b","tags":["x_refsource_MISC"],"url":"https://github.com/isomorphic-git/isomorphic-git/commit/823843d1cd19182df79bc907c767f5bcecb39a0b"},{"name":"https://github.com/isomorphic-git/isomorphic-git/releases/tag/v1.38.6","tags":["x_refsource_MISC"],"url":"https://github.com/isomorphic-git/isomorphic-git/releases/tag/v1.38.6"}],"source":{"advisory":"GHSA-9x82-4j54-863h","discovery":"UNKNOWN"},"title":"isomorphic-git: Unbounded memory allocation from attacker-controlled delta target size (DoS)"}},"cveMetadata":{"assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","assignerShortName":"GitHub_M","cveId":"CVE-2026-63476","datePublished":"2026-11-03T19:44:06.908Z","dateReserved":"2026-07-16T21:37:45.769Z","dateUpdated":"2026-11-03T19:44:06.908Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-11-03 20:18:16","lastModifiedDate":"2026-11-03 20:18:16","problem_types":["CWE-400","CWE-789","CWE-400 CWE-400: Uncontrolled Resource Consumption","CWE-789 CWE-789: Memory Allocation with Excessive Size Value"],"metrics":{"cvssMetricV31":[{"source":"security-advisories@github.com","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L","baseScore":4.3,"baseSeverity":"MEDIUM","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"REQUIRED","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"LOW"},"exploitabilityScore":2.8,"impactScore":1.4}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"63476","Ordinal":"1","Title":"isomorphic-git: Unbounded memory allocation from attacker-contro","CVE":"CVE-2026-63476","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"63476","Ordinal":"1","NoteData":"isomorphic-git is a pure JavaScript implementation of Git for Node.js and browsers. Prior to 1.38.6, isomorphic-git reads a server-controlled targetSize while applying a packfile delta in src/utils/applyDelta.js and passes it without a bound to Buffer.alloc(targetSize). A malicious or man-in-the-middle-controlled remote can send one delta header that causes git.clone() or git.fetch() to allocate approximately 2 GB before validating the actual delta output. GitPackIndex.fromPack swallows the later size-mismatch error, so a host with sufficient memory may retain the resource waste without a visible failure, while containers, serverless functions, and small virtual machines may terminate. Node.js heap limits do not mitigate the off-heap Buffer allocation. This issue is fixed in version 1.38.6.","Type":"Description","Title":"isomorphic-git: Unbounded memory allocation from attacker-contro"}]}}}