CVE-2026-25725highCWE-501CWE-668

CVE-2026-25725: high-severity vulnerability in anthropics claude-code

Claude Code Has Sandbox Escape via Persistent Configuration Injection in settings.json

Published

Follow this CVE+ Monitor claude-code+ Monitor @anthropic-ai/claude-code

E-mail alert when it lands in KEV, gets a public PoC or its score goes up.

21Vexday Risk Score

No sign of exploitation. No public exploitation artifact known so far.

ssvc Trackcvss 7.7epss 0.5%
In short

Claude Code's sandbox had a weakness where missing configuration files could be created by malicious code inside the sandbox, allowing attackers to inject commands that run with full computer privileges when the tool restarts.

Technical detail

CVE-2026-25725 exploits improper file access controls in bubblewrap sandbox initialization; attackers with code execution inside the sandbox can create .claude/settings.json and inject persistent hooks (e.g., SessionStart commands) that execute with host privileges upon tool restart, bypassing sandbox restrictions through configuration injection.

Summary generated and translated by AI from the official description.
Claude Code is an agentic coding tool. Prior to version 2.1.2, Claude Code's bubblewrap sandboxing mechanism failed to properly protect the .claude/settings.json configuration file when it did not exist at startup. While the parent directory was mounted as writable and .claude/settings.local.json was explicitly protected with read-only constraints, settings.json was not protected if it was missing. This allowed malicious code running inside the sandbox to create this file and inject persistent hooks (such as SessionStart commands) that would execute with host privileges when Claude Code was restarted. This issue has been patched in version 2.1.2.
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
Affected products
anthropics · claude-code
Related CVEs — anthropics claude-code

In the same product, most dangerous first.

CVE-2026-21852MEDIUMClaude Code Leaks Data via Malicious Environment Configuration Before Trust ConfirmationEPSS 27.5%CVE-2025-59536HIGHClaude Code's startup trust dialog could lead to Command Execution attackEPSS 24.9%CVE-2025-54794HIGHClaude Code Research Preview has a Path Restriction Bypass which could allow unauthorized file accessEPSS 1.5%CVE-2025-54795HIGHClaude Code echo command allowed bypass of user approval prompt for command executionEPSS 1.1%CVE-2025-66032HIGHClaude Code Command Validation Bypass Allows Arbitrary Code ExecutionEPSS 0.7%CVE-2026-39861HIGHClaude Code: Sandbox Escape via Symlink Following Allows Arbitrary File Write Outside WorkspaceEPSS 0.7%