capstone-engine Capstone up to 6.0.0-Alpha8 WebAssembly Backend cs_disasm/cs_disasm_iter integer overflow

Summaryinfo

A vulnerability identified as problematic has been detected in capstone-engine Capstone up to 6.0.0-Alpha8. The affected element is the function cs_disasm/cs_disasm_iter of the component WebAssembly Backend. The manipulation leads to integer overflow. This vulnerability is uniquely identified as CVE-2026-49263. The attack is possible to be carried out remotely. No exploit exists.

Detailsinfo

A vulnerability was found in capstone-engine Capstone up to 6.0.0-Alpha8. It has been rated as problematic. This issue affects the function cs_disasm/cs_disasm_iter of the component WebAssembly Backend. The manipulation with an unknown input leads to a integer overflow vulnerability. Using CWE to declare the problem leads to CWE-190. The product performs a calculation that can produce an integer overflow or wraparound, when the logic assumes that the resulting value will always be larger than the original value. This can introduce other weaknesses when the calculation is used for resource management or execution control. Impacted is availability. The summary by CVE is:

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.

The advisory is shared at github.com. The identification of this vulnerability is CVE-2026-49263 since 05/28/2026. The exploitation is known to be easy. The attack may be initiated remotely. It demands that the victim is doing some kind of user interaction. Technical details are known, but no exploit is available.

Upgrading to version 6.0.0-Alpha9 eliminates this vulnerability.

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Productinfo

Vendor

• capstone-engine

Name

• Capstone

Version

• 6.0.0-Alpha8

Website

• Product: https://github.com/capstone-engine/capstone/

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