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CVE-2026-55893— Capstone SH disassembler `set_reg_n` heap buffer overflow via crafted SH2A FPU bytecode

Quick assessment

Affected
capstone-engine capstone
Exploitation
Public or AI PoC available; prioritize validation
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

capstone-engine Capstone Engine是capstone-engine团队开源的一套反汇编引擎框架。 Capstone Engine 6.0.0-Alpha10之前版本存在缓冲区错误漏洞，该漏洞源于SH浮点解码器调用set_reg()和set_reg_n()时未检查固定大小的operands[]数组，导致堆缓冲区溢出，可能造成进程崩溃或代码执行。

CVSS 7.3 · High EPSS 0.19% · P8

Possible ATT&CK Techniques 1 AI

T1203 · Exploitation for Client Execution

Affected Version Matrix 1

VendorProduct Version RangeStatus
capstone-engine capstone < 6.0.0-Alpha10 affected
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I. Basic Information for CVE-2026-55893

Vulnerability Information
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Vulnerability Title
Capstone SH disassembler `set_reg_n` heap buffer overflow via crafted SH2A FPU bytecode
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:L/AC:H/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
堆缓冲区溢出
Source: CVE Program / CVE List V5
Vulnerability Title
Capstone Engine 缓冲区错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
capstone-engine Capstone Engine是capstone-engine团队开源的一套反汇编引擎框架。 Capstone Engine 6.0.0-Alpha10之前版本存在缓冲区错误漏洞，该漏洞源于SH浮点解码器调用set_reg()和set_reg_n()时未检查固定大小的operands[]数组，导致堆缓冲区溢出，可能造成进程崩溃或代码执行。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
capstone-engine capstone < 6.0.0-Alpha10 -

II. Public POCs for CVE-2026-55893

# POC Description Source Link Shenlong Link
AI-Generated POC Verified env Premium
Reproduced successfully in a real sandbox · Below is the actual recording of building the environment and exploiting the vulnerability.
Success marker: VULNERABLE: free(): invalid pointer (exit 134) - SH FPU heap buffer overflow in Capstone
Reproduction recording is a Pro+ exclusive
Watch the full sandbox build + live exploit recording for this CVE. Limited-time ¥499/mo.
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claude_code · 8661 chars
GitHub 复现环境（可 clone 直接跑）
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III. Intelligence Information for CVE-2026-55893

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Patches & Fixes for CVE-2026-55893 (4)

Vendor Advisories for CVE-2026-55893 (1)

Vendor Pages for CVE-2026-55893 (1)

IV. Related Vulnerabilities

Same product: capstone
Same vendor: capstone-engine
Same weakness: CWE-122