CVE-2026-35603
Published: 17 April 2026
Summary
CVE-2026-35603 is a medium-severity Untrusted Search Path (CWE-426) vulnerability in Anthropic Claude Code. Its CVSS base score is 5.4 (Medium).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 1.9th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
This vulnerability is AI-related — categorised as Enterprise AI Assistants; in the Supply Chain and Deployment risk domain.
The strongest mitigations our analysis identified are NIST 800-53 CM-5 (Access Restrictions for Change) and SC-4 (Information in Shared System Resources).
Deeper analysis
CVE-2026-35603 affects Claude Code, an agentic coding tool, in versions prior to 2.1.75 on Windows. The vulnerability stems from the application loading a system-wide default configuration file from the path C:\ProgramData\ClaudeCode\managed-settings.json without validating directory ownership or access permissions. The ProgramData directory is writable by non-administrative users by default, and the ClaudeCode subdirectory is neither pre-created nor access-restricted, enabling unauthorized file placement (CWE-426: Untrusted Search Path). The issue was published on 2026-04-17.
A low-privileged local user can exploit this on a shared multi-user Windows system by creating the C:\ProgramData\ClaudeCode directory and placing a malicious managed-settings.json file. When any other user, such as an administrator, launches Claude Code afterward, the malicious configuration is automatically loaded. This requires user interaction from the victim (UI:R) but grants the attacker high-impact confidentiality, integrity, and availability compromise (CVSS 7.3: AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H).
The vulnerability has been fixed in Claude Code version 2.1.75. Additional mitigation details are available in the security advisory at https://github.com/anthropics/claude-code/security/advisories/GHSA-5cwg-9f6j-9jvx.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-23520
Vulnerability details
Claude Code is an agentic coding tool. In versions prior to 2.1.75 on Windows, Claude Code loaded the system-wide default configuration from C:\ProgramData\ClaudeCode\managed-settings.json without validating directory ownership or access permissions. Because the ProgramData directory is writable by non-administrative users by…
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default and the ClaudeCode subdirectory was not pre-created or access-restricted, a low-privileged local user could create this directory and place a malicious configuration file that would be automatically loaded for any user launching Claude Code on the same machine. Exploiting this would have required a shared multi-user Windows system and a victim user to launch Claude Code after the malicious configuration was placed. This issue has been fixed on version 2.1.75.
- CWE(s)
AI Security AnalysisAI
- AI Category
- Enterprise AI Assistants
- Risk Domain
- Supply Chain and Deployment
- OWASP Top 10 for LLMs 2025
- None mapped
- Classification Reason
- Matched keywords: claude
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Vulnerability allows low-privileged placement of malicious config file in expected system path (C:\ProgramData\ClaudeCode) due to missing ownership/permission checks, enabling path interception via search order and exploitation for privilege escalation when higher-privileged users launch the application.
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Prevents unauthorized information transfer via shared system resources like the writable ProgramData directory by requiring validation of directory ownership and permissions before loading configuration files.
Requires validation of configuration inputs from untrusted paths to block malicious managed-settings.json files from being processed.
Restricts creation and modification of configuration directories and files in shared locations like C:\ProgramData\ClaudeCode to authorized users, preventing low-privileged exploitation.