Claude Code: TOCTOU Race in Edit Tool Allows File Writes Outside the Workspace

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

7.7 · CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2026-88968: 0.32% estimated exploitation activity in the next 30 days; percentile 24.90 (FIRST EPSS, 2026-11-10). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Claude Code validated Edit tool targets using point-in-time pathname and symlink resolution that was not bound to the underlying directory inodes or file descriptors. On macOS, a process running inside Claude Code's Bash sandbox could exploit the resulting time-of-check to time-of-use window by atomically swapping an in-workspace parent directory with a symlink after validation completed, causing the unsandboxed Edit implementation to overwrite an attacker-selected user-writable file outside the workspace. Exploiting this required the ability to run attacker-controlled code inside the sandbox, such as through a malicious repository or dependency script. Users on standard Claude Code auto-update have received this fix automatically. Users performing manual updates are advised to update to the latest version. Claude Code thanks hackerone.com/mahoraga007 (Sunder Singh) for reporting this issue.

Published by the source

9 Nov 2026, 22:42 UTC

Last modified by the source

9 Nov 2026, 23:00 UTC

Source last checked

10 Nov 2026, 06:25 UTC

1. Revision 2 · amended · 10 Nov 2026

   Amended from osv record GHSA-5xjx-9qx6-jcrv

2. Revision 1 · created · 9 Nov 2026

   Published from ghsa record GHSA-5xjx-9qx6-jcrv

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# Patch Next advisory brief: CVE-2026-88968

Advisory: Claude Code: TOCTOU Race in Edit Tool Allows File Writes Outside the Workspace
IDs: CVE-2026-88968, GHSA-5xjx-9qx6-jcrv
Record: https://patchnext.com/advisories/cve-2026-88968 (revision 2, source checked 10 Nov 2026, 06:25 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: @anthropic-ai/claude-code 2.1.251. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm @anthropic-ai/claude-code: affected < 2.1.251; fixed in 2.1.251

## Suggested inspection (read-only)
- `npm ls @anthropic-ai/claude-code --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on @anthropic-ai/claude-code.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-5xjx-9qx6-jcrv (GitHub-reviewed advisory GHSA-5xjx-9qx6-jcrv lists affected ranges: npm @anthropic-ai/claude-code >=0 <2.1.251)
- Verified: https://osv.dev/vulnerability/GHSA-5xjx-9qx6-jcrv (OSV record GHSA-5xjx-9qx6-jcrv lists affected ranges: npm @anthropic-ai/claude-code >=0 <2.1.251 (fixed))

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