High
py7zr — security advisory
py7zr is a Python-based library and utility to support 7zip archive compression, decompression, encryption and decryption. Prior to 1.1.3, PackInfo._read() in archiveinfo.py used an O(n^2) cumulative sum pattern for attacker-controlled numstreams values parsed from archive headers, allowing a crafted .7z archive to cause excessive CPU consumption during SevenZipFile.init() before extraction. This issue is fixed in version 1.1.3.
- Products
- py7zr
- Affected versions
- 0.11.3+dfsg-1, 0.11.3+dfsg-1ubuntu1, 0.11.3+dfsg-2, 0.11.3+dfsg-3, 0.11.3+dfsg-4, 0.11.3+dfsg-4ubuntu0.1, 0.11.3+dfsg-6, 0.11.3+dfsg-7, 0.11.3+dfsg-8, 0.11.3+dfsg-8build1, 0.22.0+dfsg-1, 1.0.0+dfsg1-1, 1.0.0+dfsg1-3, 1.0.0+dfsg1-4, 1.0.0+dfsg1-5, 1.1.2+dfsg-1, 1.1.2-1+really1.1.0+dfsg-2, 1.1.3+dfsg-1
- Fixed versions
- Not specified
- CVEs
- CVE-2026-55206
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 03:09 UTC · Revision 1
Source evidence
py7zr is a Python-based library and utility to support 7zip archive compression, decompression, encryption and decryption. Prior to 1.1.3, PackInfo._read() in archiveinfo.py used an O(n^2) cumulative sum pattern for attacker-controlled numstreams values parsed from archive headers, allowing a crafted .7z archive to cause excessive CPU consumption during SevenZipFile.init() before extraction. This issue is fixed in version 1.1.3.
osv:UBUNTU-CVE-2026-55206
py7zr
Fixed versions: Not specified
py7zr
Fixed versions: Not specified
py7zr
Fixed versions: Not specified
py7zr
Fixed versions: Not specified
py7zr
Fixed versions: Not specified
Complete source record
{
"id": "dffa2060e950cd6e1659c870e18e95920396ebba63cd2032669b38b643c7edad",
"url": "https://osv.dev/vulnerability/UBUNTU-CVE-2026-55206",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "UBUNTU-CVE-2026-55206",
"summary": "py7zr is a Python-based library and utility to support 7zip archive compression, decompression, encryption and decryption. Prior to 1.1.3, PackInfo._read() in archiveinfo.py used an O(n^2) cumulative sum pattern for attacker-controlled numstreams values parsed from archive headers, allowing a crafted .7z archive to cause excessive CPU consumption during SevenZipFile.init() before extraction. This issue is fixed in version 1.1.3.",
"evidence": "osv:UBUNTU-CVE-2026-55206",
"products": [
{
"name": {
"value": "py7zr",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "0.11.3+dfsg-1",
"evidence": "/affected/0/versions"
},
{
"value": "0.11.3+dfsg-1ubuntu1",
"evidence": "/affected/0/versions"
},
{
"value": "0.11.3+dfsg-2",
"evidence": "/affected/0/versions"
},
{
"value": "0.11.3+dfsg-3",
"evidence": "/affected/0/versions"
},
{
"value": "0.11.3+dfsg-4",
"evidence": "/affected/0/versions"
},
{
"value": "0.11.3+dfsg-4ubuntu0.1",
"evidence": "/affected/0/versions"
}
]
},
{
"name": {
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"evidence": "/affected/1/package/name"
},
"prerequisites": [],
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"affected_versions": [
{
"value": "0.11.3+dfsg-6",
"evidence": "/affected/1/versions"
},
{
"value": "0.11.3+dfsg-7",
"evidence": "/affected/1/versions"
},
{
"value": "0.11.3+dfsg-8",
"evidence": "/affected/1/versions"
},
{
"value": "0.11.3+dfsg-8build1",
"evidence": "/affected/1/versions"
}
]
},
{
"name": {
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"evidence": "/affected/2/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "0.22.0+dfsg-1",
"evidence": "/affected/2/versions"
},
{
"value": "1.0.0+dfsg1-1",
"evidence": "/affected/2/versions"
}
]
},
{
"name": {
"value": "py7zr",
"evidence": "/affected/3/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.1.2+dfsg-1",
"evidence": "/affected/3/versions"
},
{
"value": "1.1.2-1+really1.1.0+dfsg-2",
"evidence": "/affected/3/versions"
},
{
"value": "1.1.3+dfsg-1",
"evidence": "/affected/3/versions"
}
]
},
{
"name": {
"value": "py7zr",
"evidence": "/affected/4/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.0.0+dfsg1-1",
"evidence": "/affected/4/versions"
},
{
"value": "1.0.0+dfsg1-3",
"evidence": "/affected/4/versions"
},
{
"value": "1.0.0+dfsg1-4",
"evidence": "/affected/4/versions"
},
{
"value": "1.0.0+dfsg1-5",
"evidence": "/affected/4/versions"
},
{
"value": "1.1.2+dfsg-1",
"evidence": "/affected/4/versions"
}
]
}
],
"severity": "high",
"structured": {
"id": "UBUNTU-CVE-2026-55206",
"aliases": [
"UBUNTU-CVE-2026-55206"
],
"metrics": [
{
"type": "CVSS_V4",
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N"
},
{
"type": "Ubuntu",
"score": "medium"
}
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "py7zr",
"purl": "pkg:deb/ubuntu/py7zr?arch=source&distro=jammy",
"ecosystem": "Ubuntu:22.04:LTS"
},
"versions": [
"0.11.3+dfsg-1",
"0.11.3+dfsg-1ubuntu1",
"0.11.3+dfsg-2",
"0.11.3+dfsg-3",
"0.11.3+dfsg-4",
"0.11.3+dfsg-4ubuntu0.1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-55206.json"
},
"ecosystem_specific": {
"binaries": [
{
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"binary_version": "0.11.3+dfsg-4ubuntu0.1"
}
]
}
},
{
"ranges": [
{
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}
]
}
],
"package": {
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"purl": "pkg:deb/ubuntu/py7zr?arch=source&distro=noble",
"ecosystem": "Ubuntu:24.04:LTS"
},
"versions": [
"0.11.3+dfsg-6",
"0.11.3+dfsg-7",
"0.11.3+dfsg-8",
"0.11.3+dfsg-8build1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-55206.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "python3-py7zr",
"binary_version": "0.11.3+dfsg-8build1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
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}
]
}
],
"package": {
"name": "py7zr",
"purl": "pkg:deb/ubuntu/py7zr?arch=source&distro=questing",
"ecosystem": "Ubuntu:25.10"
},
"versions": [
"0.22.0+dfsg-1",
"1.0.0+dfsg1-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-55206.json"
},
"ecosystem_specific": {
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{
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}
]
}
},
{
"ranges": [
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{
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],
"package": {
"name": "py7zr",
"purl": "pkg:deb/ubuntu/py7zr?arch=source&distro=stonking",
"ecosystem": "Ubuntu:26.10"
},
"versions": [
"1.1.2+dfsg-1",
"1.1.2-1+really1.1.0+dfsg-2",
"1.1.3+dfsg-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-55206.json"
},
"ecosystem_specific": {
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{
"binary_name": "python3-py7zr",
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]
}
},
{
"ranges": [
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"package": {
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"ecosystem": "Ubuntu:26.04:LTS"
},
"versions": [
"1.0.0+dfsg1-1",
"1.0.0+dfsg1-3",
"1.0.0+dfsg1-4",
"1.0.0+dfsg1-5",
"1.1.2+dfsg-1"
],
"database_specific": {
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},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "python3-py7zr",
"binary_version": "1.1.2+dfsg-1"
}
]
}
}
],
"modified": "2026-10-17T13:00:27.032752922Z",
"provider": "osv",
"upstream": [
"CVE-2026-55206"
],
"references": [
"https://ubuntu.com/security/CVE-2026-55206",
"https://www.cve.org/CVERecord?id=CVE-2026-55206",
"https://github.com/miurahr/py7zr/commit/d7aa3a197d15c75a65b24f796d3a69f83806d3f8",
"https://github.com/miurahr/py7zr/releases/tag/v1.1.3",
"https://github.com/miurahr/py7zr/security/advisories/GHSA-h4gh-22qq-72r7"
]
},
"related_cves": [
{
"value": "CVE-2026-55206",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 360559,
"published_at": "2026-07-08T21:16:00+00:00"
}