High
cbor2 — security advisory
cbor2 provides encoding and decoding for the Concise Binary Object Representation (CBOR) serialization format. Starting in version 3.0.0 and prior to version 5.8.0, whhen a CBORDecoder instance is reused across multiple decode operations, values marked with the shareable tag (28) persist in memory and can be accessed by subsequent CBOR messages using the sharedref tag (29). This allows an attacker-controlled message to read data from previously decoded messages if the decoder is reused across trust boundaries. Version 5.8.0 patches the issue.
- Products
- cbor2
- Affected versions
- 5.2.0-4, 5.2.0-4build1, 5.4.2-1, 5.4.2-1build1, 5.4.6-2, 5.4.6-2build1, 5.5.1-1, 5.6.0-1, 5.6.1-1, 5.6.2-1, 5.6.2-1build1, 5.6.5-1build1, 5.7.0-1, 5.7.1-1, 5.8.0-1, 5.8.0-2ubuntu1, 6.1.2-2
- Fixed versions
- Not specified
- CVEs
- CVE-2025-68131
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 01:55 UTC · Revision 1
Source evidence
cbor2 provides encoding and decoding for the Concise Binary Object Representation (CBOR) serialization format. Starting in version 3.0.0 and prior to version 5.8.0, whhen a CBORDecoder instance is reused across multiple decode operations, values marked with the shareable tag (28) persist in memory and can be accessed by subsequent CBOR messages using the sharedref tag (29). This allows an attacker-controlled message to read data from previously decoded messages if the decoder is reused across trust boundaries. Version 5.8.0 patches the issue.
osv:UBUNTU-CVE-2025-68131
cbor2
Fixed versions: Not specified
cbor2
Fixed versions: Not specified
cbor2
Fixed versions: Not specified
cbor2
Fixed versions: Not specified
cbor2
Fixed versions: Not specified
Complete source record
{
"id": "b3b64a60e83915fa2a013531c087f42ccbb44be5f5b2881403f532b9503efb92",
"url": "https://osv.dev/vulnerability/UBUNTU-CVE-2025-68131",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "UBUNTU-CVE-2025-68131",
"summary": "cbor2 provides encoding and decoding for the Concise Binary Object Representation (CBOR) serialization format. Starting in version 3.0.0 and prior to version 5.8.0, whhen a CBORDecoder instance is reused across multiple decode operations, values marked with the shareable tag (28) persist in memory and can be accessed by subsequent CBOR messages using the sharedref tag (29). This allows an attacker-controlled message to read data from previously decoded messages if the decoder is reused across trust boundaries. Version 5.8.0 patches the issue.",
"evidence": "osv:UBUNTU-CVE-2025-68131",
"products": [
{
"name": {
"value": "cbor2",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "5.2.0-4",
"evidence": "/affected/0/versions"
},
{
"value": "5.2.0-4build1",
"evidence": "/affected/0/versions"
},
{
"value": "5.4.2-1",
"evidence": "/affected/0/versions"
},
{
"value": "5.4.2-1build1",
"evidence": "/affected/0/versions"
}
]
},
{
"name": {
"value": "cbor2",
"evidence": "/affected/1/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "5.4.6-2",
"evidence": "/affected/1/versions"
},
{
"value": "5.4.6-2build1",
"evidence": "/affected/1/versions"
},
{
"value": "5.5.1-1",
"evidence": "/affected/1/versions"
},
{
"value": "5.6.0-1",
"evidence": "/affected/1/versions"
},
{
"value": "5.6.1-1",
"evidence": "/affected/1/versions"
},
{
"value": "5.6.2-1",
"evidence": "/affected/1/versions"
},
{
"value": "5.6.2-1build1",
"evidence": "/affected/1/versions"
}
]
},
{
"name": {
"value": "cbor2",
"evidence": "/affected/2/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "5.6.5-1build1",
"evidence": "/affected/2/versions"
}
]
},
{
"name": {
"value": "cbor2",
"evidence": "/affected/3/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "5.8.0-2ubuntu1",
"evidence": "/affected/3/versions"
},
{
"value": "6.1.2-2",
"evidence": "/affected/3/versions"
}
]
},
{
"name": {
"value": "cbor2",
"evidence": "/affected/4/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "5.6.5-1build1",
"evidence": "/affected/4/versions"
},
{
"value": "5.7.0-1",
"evidence": "/affected/4/versions"
},
{
"value": "5.7.1-1",
"evidence": "/affected/4/versions"
},
{
"value": "5.8.0-1",
"evidence": "/affected/4/versions"
},
{
"value": "5.8.0-2ubuntu1",
"evidence": "/affected/4/versions"
}
]
}
],
"severity": "high",
"structured": {
"id": "UBUNTU-CVE-2025-68131",
"aliases": [
"UBUNTU-CVE-2025-68131"
],
"metrics": [
{
"type": "CVSS_V4",
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:L/SC:N/SI:N/SA:N/E:P"
},
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N"
},
{
"type": "Ubuntu",
"score": "medium"
}
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "cbor2",
"purl": "pkg:deb/ubuntu/cbor2?arch=source&distro=jammy",
"ecosystem": "Ubuntu:22.04:LTS"
},
"versions": [
"5.2.0-4",
"5.2.0-4build1",
"5.4.2-1",
"5.4.2-1build1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2025/UBUNTU-CVE-2025-68131.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "python3-cbor2",
"binary_version": "5.4.2-1build1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "cbor2",
"purl": "pkg:deb/ubuntu/cbor2?arch=source&distro=noble",
"ecosystem": "Ubuntu:24.04:LTS"
},
"versions": [
"5.4.6-2",
"5.4.6-2build1",
"5.5.1-1",
"5.6.0-1",
"5.6.1-1",
"5.6.2-1",
"5.6.2-1build1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2025/UBUNTU-CVE-2025-68131.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "python3-cbor2",
"binary_version": "5.6.2-1build1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "cbor2",
"purl": "pkg:deb/ubuntu/cbor2?arch=source&distro=questing",
"ecosystem": "Ubuntu:25.10"
},
"versions": [
"5.6.5-1build1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2025/UBUNTU-CVE-2025-68131.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "python3-cbor2",
"binary_version": "5.6.5-1build1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "cbor2",
"purl": "pkg:deb/ubuntu/cbor2?arch=source&distro=stonking",
"ecosystem": "Ubuntu:26.10"
},
"versions": [
"5.8.0-2ubuntu1",
"6.1.2-2"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2025/UBUNTU-CVE-2025-68131.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "python3-cbor2",
"binary_version": "6.1.2-2"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "cbor2",
"purl": "pkg:deb/ubuntu/cbor2?arch=source&distro=resolute",
"ecosystem": "Ubuntu:26.04:LTS"
},
"versions": [
"5.6.5-1build1",
"5.7.0-1",
"5.7.1-1",
"5.8.0-1",
"5.8.0-2ubuntu1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2025/UBUNTU-CVE-2025-68131.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "python3-cbor2",
"binary_version": "5.8.0-2ubuntu1"
}
]
}
}
],
"modified": "2026-10-17T12:57:38.791218160Z",
"provider": "osv",
"upstream": [
"CVE-2025-68131"
],
"references": [
"https://ubuntu.com/security/CVE-2025-68131",
"https://www.cve.org/CVERecord?id=CVE-2025-68131",
"https://github.com/agronholm/cbor2/security/advisories/GHSA-wcj4-jw5j-44wh",
"https://github.com/agronholm/cbor2/pull/268"
]
},
"related_cves": [
{
"value": "CVE-2025-68131",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/1/score"
},
"source_id": "core-osv",
"document_id": 357658,
"published_at": "2025-12-31T02:15:00+00:00"
}