Capstone 6.0.0-Alpha9 Ships Security Fixes

Capstone, the lightweight multi-platform disassembly framework, released version 6.0.0-Alpha9 on May 29, 2026. This alpha fixes security advisories GHSA-5m9f-vqcm-g5pr and GHSA-jrw4-wj52-2vw8, and updates the pre-release version string in capstone.h. The stable branch also got a patch: version 5.0.9, released May 28, backports those CVE fixes and sets the correct version number in CS_VERSION_EXTRA.

What Capstone Does

Capstone is a disassembly engine—it converts machine code back into human-readable assembly instructions. It supports 22+ architectures: ARM, ARM64 (ARMv8), BPF, Ethereum VM, M68K, M680X, Mips, MOS65XX, PowerPC, RISC-V, SH, Sparc, SystemZ, TMS320C64X, TriCore, Webassembly, XCore, and x86 (16, 32, 64). The API is clean, simple, and architecture-neutral. It provides detailed instruction decomposition and semantics (e.g., implicit registers read/written).

Recent Release History

Technical Details

Capstone is implemented in pure C, with bindings for D, Clojure, F#, Common Lisp, Visual Basic, PHP, PowerShell, Haskell, Perl, Python, Ruby, C#, NodeJS, Java, GO, C++, OCaml, Lua, Rust, Delphi, Free Pascal, and Vala. It natively supports Windows, *nix (Mac OSX, iOS, Android, Linux, *BSD, Solaris). It is thread-safe by design and suitable for embedding into firmware or OS kernel. The engine handles various x86 malware tricks and is distributed under the BSD license.

Why It Matters for Developers

If you work in reverse engineering, binary analysis, or security, Capstone is the standard disassembly framework. It's used in tools like radare2, Binary Ninja, and many malware analysis pipelines. The frequent alpha releases indicate active development toward a stable 6.0.0 release. The security fixes in Alpha9 and 5.0.9 address vulnerabilities that could affect downstream tools. The addition of ColdFire ISA and Apple proprietary AArch64 instructions shows the project keeps pace with new hardware.

Using Capstone

Here's a minimal example in C to disassemble a single x86-64 instruction:

#include 

int main() {
    csh handle;
    cs_insn *insn;
    size_t count;
    uint8_t code[] = {0x55, 0x48, 0x8b, 0x05, 0xb8, 0x13, 0x00, 0x00}; // example bytes
    if (cs_open(CS_ARCH_X86, CS_MODE_64, &handle) != CS_ERR_OK) return -1;
    count = cs_disasm(handle, code, sizeof(code), 0x1000, 0, &insn);
    if (count > 0) {
        for (size_t j = 0; j < count; j++) {
            printf("0x%lx: %s %s\n", insn[j].address, insn[j].mnemonic, insn[j].op_str);
        }
        cs_free(insn, count);
    }
    cs_close(&handle);
    return 0;
}

Community and Testimonials

Capstone has broad industry support. George Hotz called it "something people have wanted for years." Felix Lindner said "Capstone has changed the Reverse Engineering landscape." Bruce Dang predicted it would become the standard disassembly engine. The project has 16.8k stars on GitHub and is actively maintained with multiple releases per month.

Next Steps

Check the release notes for 6.0.0-Alpha9 at https://github.com/capstone-engine/capstone/releases/tag/6.0.0-Alpha9. If you're using Capstone in production, upgrade to 5.0.9 for the security fixes. For new projects, consider using the 6.0.0 alpha series to get the latest features, but expect potential breaking changes before the stable release.