Interpreter crash via unchecked method-table index
Published Jul 6, 2026 · Updated Jul 6, 2026
Out-of-bounds read in mruby/c 3.4.1 and earlier allows attackers to crash the interpreter by running untrusted bytecode. In mrbc_find_method(), a lower-bound search can leave right equal to num_builtin_method, yet the function still reads method_symbols[right] one element past the table. Exploitation requires an application to execute attacker-controlled .mrb bytecode, terminating the interpreter or disrupting its host application.
Summary
What happened
Out-of-bounds read in mruby/c 3.4.1 and earlier allows attackers to crash the interpreter by running untrusted bytecode. In mrbc_find_method(), a lower-bound search can leave right equal to num_builtin_method, yet the function still reads method_symbols[right] one element past the table. Exploitation requires an application to execute attacker-controlled .mrb bytecode, terminating the interpreter or disrupting its host application.
The record
- CVE
- CVE-2026-38973
- Published
- Jul 6, 2026
- Updated
- Jul 6, 2026
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- T1499.004
- Attack vector
- Unavailable
- Privileges
- Unavailable
Timeline
How it unfolded
- Jul 6, 2026CVE publishedPublication date reported by the CVE source.
- Jul 6, 2026Record updatedLatest update available in the CVE record.
Exploitability
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Attacks
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