CVE-2026-103435: Anthropic @anthropic-Ai/claude-Code

High severity, CVSS 7.7. EPSS: 0.3% chance of exploitation in the next 30 days.

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.

Affected products

• Anthropic @anthropic-Ai/claude-Code: before 2.1.129 (fixed in 2.1.129)

Published 2026-10-07. Last modified 2026-10-07.