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Vulnerability record · CVE-2026-55893 · published 20 August 2026

CVE-2026-55893: Heap-based buffer overflow vulnerability

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.

7.3 CVSS 4.0 High EPSS 0.19% · top 92.6% CWE-122 · Heap-based buffer overflow Deferred
7.3CVSS 4.0 base score
0.19%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
6References
18 Sep 2026Last modified by NVD

Description

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.

CVSS: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:

References

LinkTags
https://github.com/capstone-engine/capstone/commit/09e76802380b9e94d9720c44458d9d5282219e7e
https://github.com/capstone-engine/capstone/commit/e17ee44a8307ea33375b4727ac4f987650bf7bed
https://github.com/capstone-engine/capstone/pull/2968
https://github.com/capstone-engine/capstone/pull/2969
https://github.com/capstone-engine/capstone/releases/tag/6.0.0-Alpha10
https://github.com/capstone-engine/capstone/security/advisories/GHSA-3hpv-wr3j-rxwh

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Source: NIST National Vulnerability Database (record CVE-2026-55893), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.