Vulnerability · Published Aug 20, 2026 · Assigned by GitHub_M
CVE-2026-55894Capstone SH disassembler `sh_disassemble` out-of-bounds read via crafted SH2A bytecode
Medium 6.8
In plain English
A medium-severity out-of-bounds read in capstone from capstone-engine. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 9% of all known vulnerabilities).
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | capstone | no fix listed | DEBIAN-CVE-2026-55894 |
| Debian:13 | capstone | no fix listed | DEBIAN-CVE-2026-55894 |
| Debian:14 | capstone | no fix listed | DEBIAN-CVE-2026-55894 |
| Ubuntu:22.04:LTS | capstone | no fix listed | UBUNTU-CVE-2026-55894 |
| Ubuntu:24.04:LTS | capstone | no fix listed | UBUNTU-CVE-2026-55894 |
| Ubuntu:26.04:LTS | capstone | no fix listed | UBUNTU-CVE-2026-55894 |
| Ubuntu:26.10 | capstone | no fix listed | UBUNTU-CVE-2026-55894 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| capstone-engine | capstone | < 6.0.0-Alpha10 |
Weakness: CWE-125 · 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
References
- https://github.com/capstone-engine/capstone/security/advisories/GHSA-gf2c-xwcp-hvf4 x_refsource_CONFIRM
- https://github.com/capstone-engine/capstone/pull/2968 x_refsource_MISC
- https://github.com/capstone-engine/capstone/pull/2969 x_refsource_MISC
- https://github.com/capstone-engine/capstone/commit/09e76802380b9e94d9720c44458d9d5282219e7e x_refsource_MISC
- https://github.com/capstone-engine/capstone/commit/e17ee44a8307ea33375b4727ac4f987650bf7bed x_refsource_MISC
- https://github.com/capstone-engine/capstone/releases/tag/6.0.0-Alpha10 x_refsource_MISC