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CVE-2026-55893

Capstone SH disassembler `set_reg_n` heap buffer overflow via crafted SH2A FPU bytecode

7.3 HighFix available

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.

Attack profile

How easy it is to exploit

Attack vector
Local
Complexity
High
Privileges needed
None
User interaction
Passive

What an attacker can affect

Confidentiality
High
Integrity
High
Availability
High

Exploit likelihood

0.19%Unchanged since Aug 21, 2026
90%50%10%1%

What each source reports

CVE List Score used 7.3

Capstone SH disassembler `set_reg_n` heap buffer overflow via crafted SH2A FPU bytecode

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.

Record
CVE-2026-55893
CVSS 4.0
7.3 HighCVSS:4.0/AV:L/AC:H/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Weakness
CWE-122
Updated
2026-11-02
EUVDEUVD-2026-63673 7.3

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.

Record
EUVD-2026-63673
CVSS 4.0
7.3 HighCVSS:4.0/AV:L/AC:H/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Updated
2026-11-02
NVD 7.3

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.

Record
CVE-2026-55893
CVSS 4.0
7.3 HighCVSS:4.0/AV:L/AC:H/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Weakness
CWE-122
Updated
2026-11-02
OSV 7.3

Capstone SH disassembler `set_reg_n` heap buffer overflow via crafted SH2A FPU bytecode

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.

Record
CVE-2026-55893
CVSS 4.0
7.3 HighCVSS:4.0/AV:L/AC:H/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Weakness
CWE-122
Updated
2026-11-02
OSVDEBIAN-CVE-2026-55893 7.3

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.

Record
DEBIAN-CVE-2026-55893
CVSS 4.0
7.3 HighCVSS:4.0/AV:L/AC:H/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Updated
2026-11-02
OSVRHSA-2026:59419 7.0

Red Hat Security Advisory: Red Hat Hardened Images RPMs Security Update

Record
RHSA-2026:59419
CVSS 3.1
7.0 HighCVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVUBUNTU-CVE-2026-55893 7.3

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.

Record
UBUNTU-CVE-2026-55893
CVSS 4.0
7.3 HighCVSS:4.0/AV:L/AC:H/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Updated
2026-11-02
OSVAZL-96894 No score

CVE-2026-55893 affecting package capstone 4.0.2-4

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.

Record
AZL-96894
Updated
2026-11-02
OSVAZL-97416 No score

CVE-2026-55893 affecting package rust for versions less than 1.96.1-1

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.

Record
AZL-97416
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
capstone
Azure Linux:3
through 4.0.2-4 None known
rust
Azure Linux:3
1.85.0 up to 1.96.1-1
1.96.1-1
capstone
Alpaquita:23
4.0.2-r5 and later None known
capstone
Alpaquita:25
5.0.6-r0 and later None known
capstone
Alpaquita:stream
4.0.2-r5 and later None known
capstone
Debian:12
All versions, plus listed versions
4.0.2-54.0.2-5.15.0-1~exp15.0.1-1~exp15.0.3-1
Show 6 moreShow less
5.0.5-15.0.6-15.0.7-15.0.7-1~deb13u15.0.7-25.0.9-1
None known
capstone
Debian:13
All versions, plus listed versions
5.0.6-15.0.7-15.0.7-1~deb13u15.0.7-25.0.9-1
None known
capstone
Debian:14
All versions, plus listed versions
5.0.6-15.0.7-15.0.7-1~deb13u15.0.7-25.0.9-1
None known
capstone
Red Hat:hummingbird:1
before 0:5.0.8-0.3.hum1
0:5.0.8-0.3.hum1
capstone-devel
Red Hat:hummingbird:1
before 0:5.0.8-0.3.hum1
0:5.0.8-0.3.hum1
Show 10 moreShow less
Affected packages
PackageAffectedFixed
capstone-java
Red Hat:hummingbird:1
before 0:5.0.8-0.3.hum1
0:5.0.8-0.3.hum1
capstone-static
Red Hat:hummingbird:1
before 0:5.0.8-0.3.hum1
0:5.0.8-0.3.hum1
python3-capstone
Red Hat:hummingbird:1
before 0:5.0.8-0.3.hum1
0:5.0.8-0.3.hum1
capstone
Ubuntu:16.04:LTS
All versions, plus listed versions
3.0.4-0.13.0.4-0.2
None known
capstone
Ubuntu:18.04:LTS
All versions, plus listed versions
3.0.4-33.0.4-5
None known
capstone
Ubuntu:20.04:LTS
All versions, plus listed versions
4.0.1+really+3.0.5-14.0.1+really+3.0.5-1build1
None known
capstone
Ubuntu:22.04:LTS
All versions, plus listed versions
4.0.2-34.0.2-3build14.0.2-5
None known
capstone
Ubuntu:24.04:LTS
All versions, plus listed versions
4.0.2-54.0.2-5ubuntu14.0.2-5.14.0.2-5.1build1
None known
capstone
Ubuntu:26.10
All versions, plus listed versions
5.0.7-25.0.9-1
None known
capstone
Ubuntu:26.04:LTS
All versions, plus listed versions
5.0.6-15.0.6-1build15.0.7-2
None known

History

History
RecordedChangedSources
first indexedCVE List, EUVD, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-55893 is a high vulnerability (CVSS 7.3) in Capstone-engine Capstone, published August 20, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.19%, the 8th percentile. Fixed in rust 1.96.1-1.

References

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