capstone-engine Capstone up to 6.0.0-Alpha9 SH Floating-Point Decoders arch/SH/SHDisassembler.c set_reg/set_reg_n op_count heap-based overflow

Summaryinfo

A vulnerability, which was classified as critical, has been found in capstone-engine Capstone up to 6.0.0-Alpha9. The affected element is the function set_reg/set_reg_n of the file arch/SH/SHDisassembler.c of the component SH Floating-Point Decoders. The manipulation of the argument op_count leads to heap-based overflow. This vulnerability is referenced as CVE-2026-55893. Remote exploitation of the attack is possible. No exploit is available.

Detailsinfo

A vulnerability, which was classified as critical, has been found in capstone-engine Capstone up to 6.0.0-Alpha9. This issue affects the function set_reg/set_reg_n of the file arch/SH/SHDisassembler.c of the component SH Floating-Point Decoders. The manipulation of the argument op_count with an unknown input leads to a heap-based overflow vulnerability. Using CWE to declare the problem leads to CWE-122. A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc(). Impacted is confidentiality, integrity, and availability. The summary by CVE is:

Capstone is a disassembly framework. In 6.0.0-Alpha9 and earlier, Capstone's arch/SH/SHDisassembler.c SH floating-point decoders such as opFADD, opFMUL, and opFSUB call set_reg() and set_reg_n() using sh_info.op.op_count without checking the fixed-size operands[] array. Repeated crafted instructions processed through cs_disasm_iter() or cs_disasm() with CS_ARCH_SH, CS_MODE_SH2A or CS_MODE_SH4A, CS_MODE_SHFPU, and CS_OPT_DETAIL can increment the operand count beyond the 176-byte sh_info allocation and perform a four-byte heap buffer overflow write. The corruption can crash the process and may enable code execution depending on heap layout. This issue is fixed in version 6.0.0-Alpha10.

The advisory is shared at github.com. The identification of this vulnerability is CVE-2026-55893 since 06/17/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Technical details are known, but no exploit is available.

Upgrading to version 6.0.0-Alpha10 eliminates this vulnerability.

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Productinfo

Vendor

• capstone-engine

Name

• Capstone

Version

• 6.0.0-Alpha9

Website

• Product: https://github.com/capstone-engine/capstone/

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Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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