Capstone WASM `br_table` instruction-size truncation can cause no-progress disassembly and parser desynchronization (CVE-2026-49263) | HOL Guard CVE

Low · CVSS 2.0CVE-2026-49263

Capstone WASM `br_table` instruction-size truncation can cause no-progress disassembly and parser desynchronization

Answer in brief

CVE-2026-49263 records a Low severity (CVSS 2.0) vulnerability in Capstone WASM `br_table` instruction-size truncation can cause no-progress disassembly and parser desynchronization. The current sources do not mark it as known exploited. The current feed maps capstone-engine/capstone (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Aug 14, 2026Updated Sep 18, 2026Source checked Sep 29, 2026First seen by HOL Aug 14, 2026Material review Sep 18, 2026

Upstream Advisory

Key facts

Risk: Low · CVSS 2.0
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Available

Why this deserves its current priority

CVSS is 2.0. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps capstone-engine/capstone (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
capstone-engine/capstonegeneric	<6.0.0-Alpha9	6.0.0-Alpha9

Recommended response

Check inventory. Check lockfiles and deployed manifests for capstone-engine/capstone.
Review the reported fix. Update capstone-engine/capstone to 6.0.0-Alpha9 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Aug 14, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 18, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Aug 14, 2026

Sources and claim methodology

Upstream source 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.

Quoted source text, attributed separately from HOL analysis.