{"id":"CVE-2026-103435","title":"Claude Code validated that a target file path resided within the project working directory at permission-check time, but re-resolved the path at write time without repeating that validation","summary":"Claude Code validated that a target file path resided within the project working directory at permission-check time, but re-resolved the path at write time without repeating that validation. This time-of-check to time-of-use (TOCTOU) gap…","severity":"high","cvss":7.7,"cvssVector":"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","cwe":["CWE-22","CWE-61","CWE-367"],"vendor":"Anthropic","product":"@anthropic-ai/claude-code","affected":["@anthropic-ai/claude-code < 2.1.129"],"published":"2026-10-07","updated":"2026-10-07","sourceUpdated":"2026-10-07T13:35:14.410","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-103435","references":[{"url":"https://github.com/anthropics/claude-code/security/advisories/GHSA-5j29-h97v-84ch","label":"98a01053-8a31-4f6d-9aa9-252be161adc6"}],"tags":["nvd","cve.org"],"cvssSource":"cna","ingestedAt":"2026-10-07T13:31:04.595Z","slug":"CVE-2026-103435","body":"## Overview\n\nClaude Code validated that a target file path resided within the project working directory at permission-check time, but re-resolved the path at write time without repeating that validation. This time-of-check to time-of-use (TOCTOU) gap allowed an attacker who could write to the workspace to atomically replace a project file with a symlink, causing Claude Code to follow the symlink and write its output to an arbitrary file outside the project sandbox. Exploitation required the ability to win a race condition against the write operation and write access to the shared workspace, enabling a lower-privileged attacker to redirect benign edits to sensitive files (e.g., shell configuration) in a higher-privileged session.\n\nUsers on standard Claude Code auto-update have received this fix already. Users performing manual updates are advised to update to the latest version.\n\nThank you to hackerone.com/c_h4ck_0 for reporting this issue.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":42,"depthScoreParts":{"impact":42.4,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}