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Fencer Vulns
medium 6.1

CVE-2026-46406 json

Claude Code: Insecure Temporary File in /copy Command Enables Response Disclosure and Symlink-Based File Write

published 2026-06-25 4 mo ago modified 2026-10-25 14 d ago also GHSA-4vp2-6q8c-pvq2 , EUVD-2026-40116

cvss
6.1
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 4%
public exploits
0
none known

Summary

Claude Code is an agentic coding tool. From 2.1.59 until 2.1.128, 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. This vulnerability is fixed in 2.1.128.

Patch / fix

  • npm @anthropic-ai/claude-code 2.1.128
  • anthropic claude_code 2.1.128

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-46406 updated cvss 6.8

@anthropic-ai/claude-code: Claude Code: Information disclosure and file overwrite via insecure temporary file in /copy command

  • Red Hat OpenShift Lightspeed openshift-lightspeed/lightspeed-agentic-sandbox-rhel9
    affected: workaround, no fix available “Fix deferred”
  • Red Hat OpenShift Dev Spaces devspaces/pluginregistry-rhel9
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
4 mo ago

Exploit prediction

0.15% chance of exploitation in the next 30 days, higher than 4% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 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
CNA 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
NVD 3.1 6.1 CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:H

Affected packages

ecosystem package affected fixed in
npm @anthropic-ai/claude-code
>=2.1.59, <2.1.128
2.1.128

Affected products

  • anthropics claude-code

Classification

Weakness
  • CWE-59 Improper Link Resolution Before File Access
  • CWE-200 Exposure of Sensitive Information to an Unauthorized Actor
  • CWE-377 DEPRECATED: Insecure Temporary File

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.