CVE-2026-49263

Public on 2026-08-14
Modified on 2026-08-18
Description
Capstone is a disassembly framework. Prior to version 6.0.0-Alpha9, Capstone's WebAssembly backend accepts attacker-controlled raw WASM instruction bytes through the public `cs_disasm()` and `cs_disasm_iter()` APIs. For a large but well-formed `br_table` instruction, the WASM decoder accumulates the immediate length in a wider local variable but returns it through a `uint16_t` instruction-size path. When the encoded instruction length is exactly 65,536 bytes, the size wraps to zero and `cs_disasm()` can repeatedly decode the same instruction without advancing. For larger lengths, `cs_disasm_iter()` advances into the middle of the `br_table` payload and decodes target bytes as subsequent instructions. This is an availability and parser-integrity issue. Version 6.0.0-Alpha9 patches the issue.
Severity
Medium severity
Medium
See what this means
CVSS v3 Base Score
6.8
See breakdown

Affected Packages

Platform Package Release Date Advisory Status
Amazon Linux 2 - Core capstone Not Affected
Amazon Linux 2023 capstone Not Affected

CVSS Scores

Score Type Score Vector
Amazon Linux CVSSv3 6.8 CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H