Low
capstone — security advisory
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.
- Products
- capstone
- Affected versions
- 3.0.4-0.1, 3.0.4-0.2, 3.0.4-3, 3.0.4-5, 4.0.1+really+3.0.5-1, 4.0.1+really+3.0.5-1build1, 4.0.2-3, 4.0.2-3build1, 4.0.2-5, 4.0.2-5.1, 4.0.2-5.1build1, 4.0.2-5ubuntu1, 5.0.6-1, 5.0.6-1build1, 5.0.7-2, 5.0.9-1
- Fixed versions
- Not specified
- CVEs
- CVE-2026-49263
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 02:25 UTC · Revision 1
Source evidence
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.
osv:UBUNTU-CVE-2026-49263
capstone
Fixed versions: Not specified
capstone
Fixed versions: Not specified
capstone
Fixed versions: Not specified
capstone
Fixed versions: Not specified
capstone
Fixed versions: Not specified
capstone
Fixed versions: Not specified
capstone
Fixed versions: Not specified
Complete source record
{
"id": "9c44902b31cd4c073c5001942ae77f8949c697ea916e570f605077a013cd21f6",
"url": "https://osv.dev/vulnerability/UBUNTU-CVE-2026-49263",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "UBUNTU-CVE-2026-49263",
"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.",
"evidence": "osv:UBUNTU-CVE-2026-49263",
"products": [
{
"name": {
"value": "capstone",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "3.0.4-0.1",
"evidence": "/affected/0/versions"
},
{
"value": "3.0.4-0.2",
"evidence": "/affected/0/versions"
}
]
},
{
"name": {
"value": "capstone",
"evidence": "/affected/1/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "3.0.4-3",
"evidence": "/affected/1/versions"
},
{
"value": "3.0.4-5",
"evidence": "/affected/1/versions"
}
]
},
{
"name": {
"value": "capstone",
"evidence": "/affected/2/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "4.0.1+really+3.0.5-1",
"evidence": "/affected/2/versions"
},
{
"value": "4.0.1+really+3.0.5-1build1",
"evidence": "/affected/2/versions"
}
]
},
{
"name": {
"value": "capstone",
"evidence": "/affected/3/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "4.0.2-3",
"evidence": "/affected/3/versions"
},
{
"value": "4.0.2-3build1",
"evidence": "/affected/3/versions"
},
{
"value": "4.0.2-5",
"evidence": "/affected/3/versions"
}
]
},
{
"name": {
"value": "capstone",
"evidence": "/affected/4/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "4.0.2-5",
"evidence": "/affected/4/versions"
},
{
"value": "4.0.2-5ubuntu1",
"evidence": "/affected/4/versions"
},
{
"value": "4.0.2-5.1",
"evidence": "/affected/4/versions"
},
{
"value": "4.0.2-5.1build1",
"evidence": "/affected/4/versions"
}
]
},
{
"name": {
"value": "capstone",
"evidence": "/affected/5/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "5.0.7-2",
"evidence": "/affected/5/versions"
},
{
"value": "5.0.9-1",
"evidence": "/affected/5/versions"
}
]
},
{
"name": {
"value": "capstone",
"evidence": "/affected/6/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "5.0.6-1",
"evidence": "/affected/6/versions"
},
{
"value": "5.0.6-1build1",
"evidence": "/affected/6/versions"
},
{
"value": "5.0.7-2",
"evidence": "/affected/6/versions"
}
]
}
],
"severity": "low",
"structured": {
"id": "UBUNTU-CVE-2026-49263",
"aliases": [
"UBUNTU-CVE-2026-49263"
],
"metrics": [
{
"type": "CVSS_V4",
"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": "Ubuntu",
"score": "medium"
}
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "capstone",
"purl": "pkg:deb/ubuntu/capstone?arch=source&distro=xenial",
"ecosystem": "Ubuntu:16.04:LTS"
},
"versions": [
"3.0.4-0.1",
"3.0.4-0.2"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-49263.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libcapstone3",
"binary_version": "3.0.4-0.2"
},
{
"binary_name": "python-capstone",
"binary_version": "3.0.4-0.2"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "capstone",
"purl": "pkg:deb/ubuntu/capstone?arch=source&distro=bionic",
"ecosystem": "Ubuntu:18.04:LTS"
},
"versions": [
"3.0.4-3",
"3.0.4-5"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-49263.json"
},
"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"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "capstone",
"purl": "pkg:deb/ubuntu/capstone?arch=source&distro=focal",
"ecosystem": "Ubuntu:20.04:LTS"
},
"versions": [
"4.0.1+really+3.0.5-1",
"4.0.1+really+3.0.5-1build1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-49263.json"
},
"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"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "capstone",
"purl": "pkg:deb/ubuntu/capstone?arch=source&distro=jammy",
"ecosystem": "Ubuntu:22.04:LTS"
},
"versions": [
"4.0.2-3",
"4.0.2-3build1",
"4.0.2-5"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-49263.json"
},
"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"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "capstone",
"purl": "pkg:deb/ubuntu/capstone?arch=source&distro=noble",
"ecosystem": "Ubuntu:24.04:LTS"
},
"versions": [
"4.0.2-5",
"4.0.2-5ubuntu1",
"4.0.2-5.1",
"4.0.2-5.1build1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-49263.json"
},
"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"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "capstone",
"purl": "pkg:deb/ubuntu/capstone?arch=source&distro=stonking",
"ecosystem": "Ubuntu:26.10"
},
"versions": [
"5.0.7-2",
"5.0.9-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-49263.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "capstone-tool",
"binary_version": "5.0.9-1"
},
{
"binary_name": "libcapstone5",
"binary_version": "5.0.9-1"
},
{
"binary_name": "python3-capstone",
"binary_version": "5.0.9-1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "capstone",
"purl": "pkg:deb/ubuntu/capstone?arch=source&distro=resolute",
"ecosystem": "Ubuntu:26.04:LTS"
},
"versions": [
"5.0.6-1",
"5.0.6-1build1",
"5.0.7-2"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-49263.json"
},
"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"
}
]
}
}
],
"modified": "2026-10-17T12:58:32.271239602Z",
"provider": "osv",
"upstream": [
"CVE-2026-49263"
],
"references": [
"https://ubuntu.com/security/CVE-2026-49263",
"https://www.cve.org/CVERecord?id=CVE-2026-49263",
"https://github.com/capstone-engine/capstone/security/advisories/GHSA-5m9f-vqcm-g5pr",
"https://github.com/capstone-engine/capstone/blob/251c5bb4bc9bb92973e738ae3c5f4ef86f103356/ChangeLog#L102"
]
},
"related_cves": [
{
"value": "CVE-2026-49263",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 358715,
"published_at": "2026-08-14T18:17:00+00:00"
}