---
id: CVE-2026-49263
title: Capstone is a disassembly framework
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-…
severity: medium
cwe:
  - CWE-197
  - CWE-190
published: '2026-08-14'
updated: '2026-09-18'
sourceUpdated: '2026-09-18T20:05:53.723'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-49263'
references:
  - url: >-
      https://github.com/capstone-engine/capstone/blob/251c5bb4bc9bb92973e738ae3c5f4ef86f103356/ChangeLog#L102
    label: security-advisories@github.com
  - url: >-
      https://github.com/capstone-engine/capstone/security/advisories/GHSA-5m9f-vqcm-g5pr
    label: security-advisories@github.com
  - url: >-
      https://github.com/capstone-engine/capstone/security/advisories/GHSA-5m9f-vqcm-g5pr
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-49263.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-49263'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2516114'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-49263'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-49263'
  - url: 'https://access.redhat.com/errata/RHSA-2026:81540'
tags:
  - nvd
  - csaf
  - vex
  - red-hat
epss: 0.00171
epssPercentile: 0.06496
ingestedAt: '2026-09-18T20:51:25.617Z'
vendor: Red Hat
product: Red Hat Hardened Images
affected:
  - enterprise_linux 10
  - enterprise_linux 9
  - openshift_container_platform 4
  - hardened_images
patched:
  - hardened_images
cvss: 6.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H'
cvssSource: vendor
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Vendor advisories

- **RHSA-2026:81540** · Red Hat · fixed in: Red Hat Hardened Images · released 2026-10-12 · [advisory](https://access.redhat.com/errata/RHSA-2026:81540)
- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · updated 2026-10-16 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-49263.json)