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Vulnerability · Published Aug 20, 2026 · Assigned by GitHub_M

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

High 7.3

In plain English

A high-severity heap buffer overflow in capstone from capstone-engine. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 8% of all known vulnerabilities).

Severity (CVSS 4.0)7.3High
Exploit odds (30 days)0.2%top 91.7% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official 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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12capstoneno fix listedDEBIAN-CVE-2026-55893
Debian:13capstoneno fix listedDEBIAN-CVE-2026-55893
Debian:14capstoneno fix listedDEBIAN-CVE-2026-55893
Ubuntu:22.04:LTScapstoneno fix listedUBUNTU-CVE-2026-55893
Ubuntu:24.04:LTScapstoneno fix listedUBUNTU-CVE-2026-55893
Ubuntu:26.04:LTScapstoneno fix listedUBUNTU-CVE-2026-55893
Ubuntu:26.10capstoneno fix listedUBUNTU-CVE-2026-55893

Affected products (as reported)

VendorProductVersions
capstone-engine capstone < 6.0.0-Alpha10

Weakness: CWE-122 · Vector: 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

References