{"id":"CVE-2026-63476","published":"2026-11-03T20:18:16.063","lastModified":"2026-11-03T20:18:16.200","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.","cvssScore":4.3,"cvssSeverity":"MEDIUM","cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L","cwes":["CWE-400","CWE-789"],"vendors":[],"products":[],"references":[{"url":"https://github.com/isomorphic-git/isomorphic-git/commit/823843d1cd19182df79bc907c767f5bcecb39a0b","tags":[]},{"url":"https://github.com/isomorphic-git/isomorphic-git/pull/2370","tags":[]},{"url":"https://github.com/isomorphic-git/isomorphic-git/releases/tag/v1.38.6","tags":[]},{"url":"https://github.com/isomorphic-git/isomorphic-git/security/advisories/GHSA-9x82-4j54-863h","tags":[]}],"exploitRefs":[{"url":"https://github.com/isomorphic-git/isomorphic-git/commit/823843d1cd19182df79bc907c767f5bcecb39a0b","tags":[]},{"url":"https://github.com/isomorphic-git/isomorphic-git/pull/2370","tags":[]},{"url":"https://github.com/isomorphic-git/isomorphic-git/releases/tag/v1.38.6","tags":[]},{"url":"https://github.com/isomorphic-git/isomorphic-git/security/advisories/GHSA-9x82-4j54-863h","tags":[]}],"hasPoc":true,"ai":null}