@anthropic-ai/claude-code has an Insecure Temporary File in /copy Command that Enables Response Disclosure and Symlink-Based File Write

Exploitation

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

CVSS 4.0

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

EPSS

• CVE-2026-46406: 0.15% estimated exploitation activity in the next 30 days; percentile 4.51 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

The Claude Code /copy command wrote responses to a hardcoded, predictable path (/tmp/claude/response.md) without UID isolation, randomness, or symlink protection. The file was created world-readable (0644) in a world-traversable directory (0755), allowing any local user to read a privileged user's Claude response, which could contain secrets or credentials. Additionally, because the path was static and predictable, a local attacker could pre-create the directory and plant a symlink at the expected file path, causing the privileged process to follow the symlink and overwrite an attacker-chosen file with the response text. Exploiting this required a local unprivileged user on the same system and a privileged user to run the /copy command. Users on standard Claude Code auto-update have received this fix already. Users performing manual updates are advised to update to the latest version. Claude Code thanks hackerone.com/ch4ck0 for reporting this issue.

Published by the source

25 Jun 2026, 16:53 UTC

Last modified by the source

9 Jul 2026, 05:15 UTC

Source last checked

26 Oct 2026, 12:56 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-4vp2-6q8c-pvq2

2. Revision 2 · amended · 24 Oct 2026

   Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-4vp2-6q8c-pvq2

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# Patch Next advisory brief: CVE-2026-46406

Advisory: @anthropic-ai/claude-code has an Insecure Temporary File in /copy Command that Enables Response Disclosure and Symlink-Based File Write
IDs: CVE-2026-46406, GHSA-4vp2-6q8c-pvq2
Record: https://patchnext.com/advisories/cve-2026-46406 (revision 3, source checked 26 Oct 2026, 12:56 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 4.4)
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 2.1.128. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm @anthropic-ai/claude-code: affected >= 2.1.59, < 2.1.128; fixed in 2.1.128

## 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://osv.dev/vulnerability/GHSA-4vp2-6q8c-pvq2 (OSV record GHSA-4vp2-6q8c-pvq2 lists affected ranges: npm @anthropic-ai/claude-code >=2.1.59 <2.1.128 (fixed))
- Verified: https://github.com/advisories/GHSA-4vp2-6q8c-pvq2 (GitHub-reviewed advisory GHSA-4vp2-6q8c-pvq2 lists affected ranges: npm @anthropic-ai/claude-code >=2.1.59 <2.1.128)

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