isomorphic-git: Arbitrary file write outside the working tree via a directory symlink during checkout (potential RCE)

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-63395
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-11-03 20:18:14 UTC
Updated2026-11-03 22:19:47 UTC
Descriptionisomorphic-git is a pure JavaScript implementation of Git for Node.js and browsers. Prior to 1.38.6, isomorphic-git's git.checkout writes new child paths through symlinked leading directory components without checking them. A malicious repository can first place a directory symlink and later replace the tree state with a child file beneath that path; the usual trigger is a clone followed by a later pull, while a single clone can trigger the issue when a symlink already exists or the consuming application accesses the tree. With Node fs on Linux or macOS, the operating system can resolve the write outside the working tree, permitting arbitrary host file writes and possible code execution. Node fs on Windows usually blocks the symlink plant without additional privilege, and browser or in-memory providers limit impact to their virtual filesystem and are affected only when they implement symlink creation and following. This issue is fixed in version 1.38.6.

Risk And Classification

Primary CVSS: v3.1 8.8 HIGH from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Problem Types: CWE-22 | CWE-59 | CWE-22 CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') | CWE-59 CWE-59: Improper Link Resolution Before File Access ('Link Following')

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary8.8HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
3.1CNADECLARED8.8HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Isomorphic-git Isomorphic-git affected < 1.38.6 Not specified

References

ReferenceSourceLinkTags
github.com/isomorphic-git/isomorphic-git/security/advisories/GHSA-9qw7-j... 134c704f-9b21-4f2e-91b3-4a467353bcc0 github.com
github.com/isomorphic-git/isomorphic-git/pull/2370 [email protected] github.com
github.com/isomorphic-git/isomorphic-git/releases/tag/v1.38.6 [email protected] github.com
github.com/isomorphic-git/isomorphic-git/commit/823843d1cd19182df79bc907... [email protected] github.com
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