CVE-2026-103435 - Arbitrary File Write via Write-Time Symlink Following (TOCTOU) in Claude Code

CVE-2026-103435 - Arbitrary File Write via Write-Time Symlink Following (TOCTOU) in Claude Code

https://cvefeed.io/rssfeed/latest.atom / Wed, 10/07/2026 - 16:51
CVE ID :CVE-2026-103435
Published : Oct. 7, 2026, 1:17 p.m. | 28 minutes ago
Description :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.
Severity: 7.7 | HIGH
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