CVE-2026-49263 (GCVE-0-2026-49263)

Vulnerability from cvelistv5 – Published: 2026-08-14 17:49 – Updated: 2026-08-17 19:52
VLAI
Title
Capstone WASM `br_table` instruction-size truncation can cause no-progress disassembly and parser desynchronization
Summary
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
2 (Low)
CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:P/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N
SSVC
Exploitation: poc Automatable: no Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-17 19:51 UTC
CWE
  • CWE-197 - Numeric Truncation Error
Assigner
References
Impacted products
Vendor Product Version
capstone-engine capstone Affected: < 6.0.0-Alpha9
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