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Schedule42High7.7VulnerabilityCVE-2026-103435No patch link observed

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 wr…

Published Oct 7, 2026, 01:17 PM UTCIngested 1d agoSource NVD(cve-db)CVE-2026-103435

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.

CVSS v4.0 base metrics

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/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
7.7

High severity

Band computed from the CVSS base score, not the source's own label — so it means the same thing across every feed.

AV

Network

Attack Vector

AC

Low

Attack Complexity

AT

Present

Attack Requirements

PR

None

Privileges Required

UI

Passive

User Interaction

VC

High

Confidentiality (Vulnerable System)

VI

High

Integrity (Vulnerable System)

VA

High

Availability (Vulnerable System)

SC

None

Confidentiality (Subsequent System)

SI

None

Integrity (Subsequent System)

SA

None

Availability (Subsequent System)

References

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