# CVE-2026-55894: Capstone SH disassembler out-of-bounds read

Source: https://junglewise.ai/threats/cve-2026-55894-capstone-sh-disassembler-out-of-bounds-read  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-08-20. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-55894 · Severity: info · Published 2026-08-20

Capstone is a disassembly framework used by binary analysis tools and security software to interpret machine code. A flaw in its SH (SuperH) architecture decoder allows malicious or malformed bytecode to trigger an out-of-bounds memory read, crashing the application. While no code execution occurs, this denial-of-service impact could interrupt critical analysis workflows or be chained with other vulnerabilities.

## Quick answers

**Is CVE-2026-55894 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-55894 being exploited in the wild.

**How severe is CVE-2026-55894?** Informational severity, published 20 August 2026.

**Which products and versions are affected?** Capstone Capstone 6.0.0-Alpha9 and earlier.

**Is there a fix for CVE-2026-55894?** A patch was published on 2026-06-18: Fixed in version 6.0.0-Alpha10 and v5 branch Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-55894 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-55894?** Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The vulnerability is an out-of-bounds read in arch/SH/SHDisassembler.c's sh_disassemble() function. When processing crafted 16-bit SH instructions with architectures CS_MODE_SH2A, CS_MODE_SH4A, or CS_MODE_SHFPU, the function computes an idx value from the instruction without validating that it falls within the bounds of the mode-specific decode[] function-pointer table. An attacker can pass malicious bytecode via cs_disasm_iter() or cs_disasm() to trigger an out-of-bounds access and cause a segmentation fault, denying service to the application. No information disclosure or code execution was demonstrated. The fix was released in version 6.0.0-Alpha10 and backported to the v5 branch.

## Affected products

- Capstone Capstone 6.0.0-Alpha9 and earlier

## Timeline

- 2026-08-20: disclosed: Published on NVD
- 2026-06-18: patched: Fixed in version 6.0.0-Alpha10 and v5 branch

## References

- [https://github.com/capstone-engine/capstone/commit/09e76802380b9e94d9720c44458d9d5282219e7e](https://github.com/capstone-engine/capstone/commit/09e76802380b9e94d9720c44458d9d5282219e7e)
- [https://github.com/capstone-engine/capstone/commit/e17ee44a8307ea33375b4727ac4f987650bf7bed](https://github.com/capstone-engine/capstone/commit/e17ee44a8307ea33375b4727ac4f987650bf7bed)