Compiler crash via unchecked definition arguments
Published Feb 21, 2026 · Updated Feb 21, 2026
Out-of-bounds read in Janet 1.40.0 through 1.40.1 allows local users to crash the compiler with a malformed definition form. In handleattr, binding-name processing reads argv[0] before confirming that the definition supplies the required arguments, placing the read beyond an empty argument tuple. Exploitation requires control of source compiled by the targeted Janet process; the demonstrated consequence is a heap-buffer-overflow and process crash, not code execution.
Summary
What happened
Out-of-bounds read in Janet 1.40.0 through 1.40.1 allows local users to crash the compiler with a malformed definition form. In handleattr, binding-name processing reads argv[0] before confirming that the definition supplies the required arguments, placing the read beyond an empty argument tuple. Exploitation requires control of source compiled by the targeted Janet process; the demonstrated consequence is a heap-buffer-overflow and process crash, not code execution.
The record
- CVE
- CVE-2026-2869
- Published
- Feb 21, 2026
- Updated
- Feb 21, 2026
- Vendor
- Janet Language
- Product
- Janet
- Classifications
- CWE-125, CWE-119, T1499.004
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Feb 21, 2026CVE publishedPublication date reported by the CVE source.
- Feb 21, 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=1.40.0
- Affected versionversion=1.40.1
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.
Weakness, pattern, technique
Public exploit references
- Janet malformed definition reproducerproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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