UBUNTU-CVE-2026-49263 (CVE-2026-49263)
Vulnerability from osv_ubuntu – Published: 2026-08-14 18:17 – Updated: 2026-08-19 11:05 – Source website
VLAI
Details
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
N/A (UNKNOWN)
References
{
"affected": [
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libcapstone3",
"binary_version": "3.0.4-0.2"
},
{
"binary_name": "python-capstone",
"binary_version": "3.0.4-0.2"
}
]
},
"package": {
"ecosystem": "Ubuntu:16.04:LTS",
"name": "capstone",
"purl": "pkg:deb/ubuntu/capstone@3.0.4-0.2?arch=source\u0026distro=xenial"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"3.0.4-0.1",
"3.0.4-0.2"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libcapstone3",
"binary_version": "3.0.4-5"
},
{
"binary_name": "python-capstone",
"binary_version": "3.0.4-5"
},
{
"binary_name": "python3-capstone",
"binary_version": "3.0.4-5"
}
]
},
"package": {
"ecosystem": "Ubuntu:18.04:LTS",
"name": "capstone",
"purl": "pkg:deb/ubuntu/capstone@3.0.4-5?arch=source\u0026distro=bionic"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"3.0.4-3",
"3.0.4-5"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "capstone-tool",
"binary_version": "4.0.1+really+3.0.5-1build1"
},
{
"binary_name": "libcapstone3",
"binary_version": "4.0.1+really+3.0.5-1build1"
},
{
"binary_name": "python-capstone",
"binary_version": "4.0.1+really+3.0.5-1build1"
},
{
"binary_name": "python3-capstone",
"binary_version": "4.0.1+really+3.0.5-1build1"
}
]
},
"package": {
"ecosystem": "Ubuntu:20.04:LTS",
"name": "capstone",
"purl": "pkg:deb/ubuntu/capstone@4.0.1+really+3.0.5-1build1?arch=source\u0026distro=focal"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"4.0.1+really+3.0.5-1",
"4.0.1+really+3.0.5-1build1"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "capstone-tool",
"binary_version": "4.0.2-5"
},
{
"binary_name": "libcapstone4",
"binary_version": "4.0.2-5"
},
{
"binary_name": "python3-capstone",
"binary_version": "4.0.2-5"
}
]
},
"package": {
"ecosystem": "Ubuntu:22.04:LTS",
"name": "capstone",
"purl": "pkg:deb/ubuntu/capstone@4.0.2-5?arch=source\u0026distro=jammy"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"4.0.2-3",
"4.0.2-3build1",
"4.0.2-5"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "capstone-tool",
"binary_version": "4.0.2-5.1build1"
},
{
"binary_name": "libcapstone4",
"binary_version": "4.0.2-5.1build1"
},
{
"binary_name": "python3-capstone",
"binary_version": "4.0.2-5.1build1"
}
]
},
"package": {
"ecosystem": "Ubuntu:24.04:LTS",
"name": "capstone",
"purl": "pkg:deb/ubuntu/capstone@4.0.2-5.1build1?arch=source\u0026distro=noble"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"4.0.2-5",
"4.0.2-5ubuntu1",
"4.0.2-5.1",
"4.0.2-5.1build1"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "capstone-tool",
"binary_version": "5.0.7-2"
},
{
"binary_name": "libcapstone5",
"binary_version": "5.0.7-2"
},
{
"binary_name": "python3-capstone",
"binary_version": "5.0.7-2"
}
]
},
"package": {
"ecosystem": "Ubuntu:26.04:LTS",
"name": "capstone",
"purl": "pkg:deb/ubuntu/capstone@5.0.7-2?arch=source\u0026distro=resolute"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"5.0.6-1",
"5.0.6-1build1",
"5.0.7-2"
]
}
],
"aliases": [],
"details": "Capstone is a disassembly framework. Prior to version 6.0.0-Alpha9, Capstone\u0027s 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.",
"id": "UBUNTU-CVE-2026-49263",
"modified": "2026-08-19T11:05:28Z",
"published": "2026-08-14T18:17:00Z",
"references": [
{
"type": "REPORT",
"url": "https://ubuntu.com/security/CVE-2026-49263"
},
{
"type": "REPORT",
"url": "https://www.cve.org/CVERecord?id=CVE-2026-49263"
},
{
"type": "REPORT",
"url": "https://github.com/capstone-engine/capstone/security/advisories/GHSA-5m9f-vqcm-g5pr"
},
{
"type": "REPORT",
"url": "https://github.com/capstone-engine/capstone/blob/251c5bb4bc9bb92973e738ae3c5f4ef86f103356/ChangeLog#L102"
}
],
"related": [],
"schema_version": "1.7.0",
"severity": [
{
"score": "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",
"type": "CVSS_V4"
},
{
"score": "medium",
"type": "Ubuntu"
}
],
"upstream": [
"CVE-2026-49263"
]
}
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Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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