CVE-2026-63395

isomorphic-git is a pure JavaScript implementation of Git for Node.js and browsers

Risk score: 68/100
CVSS: 8.8 v3.1
Published: 3 Nov 2026

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What to know

What it is: isomorphic-git has a vulnerability where a malicious repository can write to arbitrary host files and potentially execute code due to incorrect handling of symlinks. An attacker could exploit this to write to any file on the system.
Affected: {'product': 'isomorphic-git', 'version': 'prior to 1.38.6'}
Fix: Upgrade to version 1.38.6 or later
Exploitation: No known exploitation

Why it is Amber

CVSS 8.8 high
Remotely exploitable without logging in
On your watchlist: node.js

References

Original description

isomorphic-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.

Last activity 3 Nov 2026. Patch Forecast updates every hour.