Code execution via fullcommand type confusion
Published Sep 2, 2023 · Updated Jun 23, 2026
Type confusion in Vim before 9.0.1846 allows local users to execute arbitrary code when a user processes malicious input. The fullcommand() implementation reads a numeric typval through its string union member instead of converting the argument by type, turning integer data into a pointer. Execution requires a user to evaluate attacker-controlled Vim script or input that invokes fullcommand() with a number; the same path can crash the editor.
Summary
What happened
Type confusion in Vim before 9.0.1846 allows local users to execute arbitrary code when a user processes malicious input. The fullcommand() implementation reads a numeric typval through its string union member instead of converting the argument by type, turning integer data into a pointer. Execution requires a user to evaluate attacker-controlled Vim script or input that invokes fullcommand() with a number; the same path can crash the editor.
The record
- CVE
- CVE-2023-4734
- Published
- Sep 2, 2023
- Updated
- Jun 23, 2026
- Vendor
- Vim
- Product
- Vim
- Classifications
- CWE-190, T1203
- Attack vector
- local
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 2, 2023CVE 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=unspecified <9.0.1846
What conditions does exploitation require?
What is affected?
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.
Weakness, pattern, technique
Public exploit references
- huntr proof-of-concept exploitproof of concept · unverified
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Technologies
Your stack
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Your stack
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