NULL Pointer Dereference Affecting capstone package, versions [0,]
Threat Intelligence
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- published22 Jul 2026
- disclosed22 Jul 2026
- creditUnknown
Introduced: 22 Jul 2026
NewCVE-2026-47143 (opens in a new tab)How to fix?
A fix was pushed into the master branch but not yet published.
Overview
Affected versions of this package are vulnerable to NULL Pointer Dereference through modRMRequired() and decode() in arch/X86/X86DisassemblerDecoder.c. An attacker can crash any application using a reduced X86 Capstone build by supplying crafted x86/x86-64 input containing a 3DNow! opcode sequence such as 0F 0F <modrm> <imm8>. When those opcodes reach the decode path, the unsupported opcode type is left unhandled, and the disassembler dereferences a null decision table, terminating the process during disassembly.
Notes
- The crash is specific to reduced X86 builds compiled with
-DCAPSTONE_X86_REDUCE, where the 3DNow! opcode map is not handled in the vulnerablemodRMRequired()anddecode()paths. - Affected inputs are the
0F 0F <modrm> <imm8>3DNow! escape sequence; normal x86/x86-64 code paths that do not reach that opcode family are not part of this issue.
Workarounds
- Use a Capstone build without
-DCAPSTONE_X86_REDUCEwhen disassembling untrusted x86/x86-64 input, or disable the reduced X86 build in your deployment; this avoids theTHREEDNOW_MAPpath that leads to the NULL dereference and process crash.