CVE-2026-103435

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 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. Users on standard Claude Code auto-update have received this fix already. Users performing manual updates are advised to update to the latest version. Thank you to hackerone.com/c_h4ck_0 for reporting this issue.

• https://github.com/anthropics/claude-code/security/advisories/GHSA-5j29-h97v-84ch

• https://github.com/anthropics/claude-code/security/advisories/GHSA-5j29-h97v-84ch

• HIGHCVE-2014-125130PoC
• HIGHCVE-2017-20284
• HIGHCVE-2021-48011PoC
• HIGHCVE-2023-54403PoC
• MEDIUMCVE-2024-58386PoC
• HIGHCVE-2024-58387PoC
• HIGHCVE-2024-58388PoC
• MEDIUMCVE-2025-1280

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