Permission-gate bypass via unsplit shell constructs
Published Jun 23, 2026 · Updated Jun 23, 2026
Incorrect authorization in RTK’s Claude Code PreToolUse hook before 0.42.2 allows attackers to execute hidden local shell commands. The permission splitter in src/hooks/permissions.rs fails to treat newlines, background operators, and command substitutions as Bash execution boundaries, then returns exit code 0 for the visible allowed prefix. Exploitation requires the Claude hook, a matching permissive allow rule, and crafted agent input; the preserved command runs without the configured confirmation or denial.
Summary
What happened
Incorrect authorization in RTK’s Claude Code PreToolUse hook before 0.42.2 allows attackers to execute hidden local shell commands. The permission splitter in src/hooks/permissions.rs fails to treat newlines, background operators, and command substitutions as Bash execution boundaries, then returns exit code 0 for the visible allowed prefix. Exploitation requires the Claude hook, a matching permissive allow rule, and crafted agent input; the preserved command runs without the configured confirmation or denial.
The record
- CVE
- CVE-2026-54555
- Published
- Jun 23, 2026
- Updated
- Jun 23, 2026
- Vendor
- RTK AI Labs
- Product
- RTK
- Classifications
- CWE-863, T1059.004
- Attack vector
- local
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jun 23, 2026CVE publishedPublication date reported by the CVE source.
- Jun 23, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 0.42.2
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
- GHSA-7gxq-fvfc-g327 direct and end-to-end proof of conceptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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