CVE-2026-55894 capstone-engine CVE debrief

Who should care

Defenders responsible for systems using Capstone's disassembly framework, particularly those handling SH architecture with SH2A or SH4A and SHFPU modes, should assess exposure and prioritize updating to version 6.0.0-Alpha10 or later.

Why it matters

Defenders should care about CVE-2026-55894 because it can cause segmentation faults in systems using Capstone's disassembly framework with specific architectures and modes. Updating to version 6.0.0-Alpha10 or later is necessary to prevent potential crashes.

• Potential crashes due to segmentation faults
• Need to verify and update vulnerable systems
• Possible impact on system stability and availability

Technical summary

The SHDisassembler.c file in Capstone's disassembly framework does not ensure the idx value computed from a raw 16-bit instruction is within the active mode-specific decode[] function-pointer table. This can cause a segmentation fault when processing crafted bytecode with CS_ARCH_SH and CS_MODE_SH2A or CS_MODE_SH4A and CS_MODE_SHFPU. The vulnerability can cause potential crashes in systems using Capstone's disassembly framework with specific architectures and modes. Updating to version 6.0.0-Alpha10 or later is necessary to prevent potential crashes.

Defensive priority

Defenders should prioritize updating to version 6.0.0-Alpha10 or later to prevent potential crashes. Systems using Capstone's disassembly framework, particularly those handling SH architecture with SH2A or SH4A and SHFPU modes, should assess exposure and verify the update.

Recommended defensive actions

• Update to Capstone version 6.0.0-Alpha10 or later
• Assess exposure in systems using Capstone's disassembly framework with SH architecture and SH2A or SH4A and SHFPU modes
• Verify the update in affected systems
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The vulnerability was demonstrated to cause a segmentation fault, but no code execution or information disclosure was shown. The issue is fixed in version 6.0.0-Alpha10. The segmentation fault occurs when processing crafted bytecode with CS_ARCH_SH and CS_MODE_SH2A or CS_MODE_SH4A and CS_MODE_SHFPU. The vulnerability was identified in Capstone's disassembly framework, specifically in the SHDisassembler.c file. No additional information about the vulnerability was provided.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.