Compiler crash via unchecked line directive metadata
Published Jun 18, 2026 · Updated Jun 18, 2026
Out-of-bounds read in Rui Ueyama 8cc b480958 allows local users to crash the compiler via crafted #line directives. The preprocessor accepts attacker-controlled filename and line-number metadata from #line directives and GNU linemarkers, then indexes source-line arrays without validating the line number. A local user must cause 8cc to compile a crafted C source file; invalid or oversized line numbers cause out-of-bounds memory access and terminate the compiler process.
Summary
What happened
Out-of-bounds read in Rui Ueyama 8cc b480958 allows local users to crash the compiler via crafted #line directives. The preprocessor accepts attacker-controlled filename and line-number metadata from #line directives and GNU linemarkers, then indexes source-line arrays without validating the line number. A local user must cause 8cc to compile a crafted C source file; invalid or oversized line numbers cause out-of-bounds memory access and terminate the compiler process.
The record
- CVE
- CVE-2026-50643
- Published
- Jun 18, 2026
- Updated
- Jun 18, 2026
- Vendor
- Rui Ueyama
- Product
- 8cc
- Classifications
- CWE-125, CAPEC-540
- Attack vector
- local
- Privileges
- Unavailable
Timeline
How it unfolded
- Jun 18, 2026CVE publishedPublication date reported by the CVE source.
- Jun 18, 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?
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- Affected versionversion=b480958
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
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Public exploit references
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Technologies
Your stack
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Your stack
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