Critical
swupdate — security advisory
SWUpdate through 2026.05.1 contains an improper certificate validation vulnerability in crypto/swupdate_cms_verify_openssl.c that trusts untrusted X.509 certificates embedded in CMS SignedData for chain building. Attackers holding a signing key from a sibling intermediate under the same root can embed that intermediate in the signature to install malicious updates.
- Products
- swupdate
- Affected versions
- 2020.11-2, 2021.04-1.1, 2021.04-2, 2021.04-2build1, 2021.11-1, 2023.05+dfsg-3, 2023.05+dfsg-4, 2023.05+dfsg-4build1, 2023.05+dfsg-5, 2023.12+dfsg-1, 2023.12.1+dfsg-1ubuntu1, 2023.12.1+dfsg-1ubuntu4, 2023.12.1+dfsg-1ubuntu5, 2025.05+dfsg-2ubuntu1, 2025.05+dfsg-3ubuntu1, 2025.12+dfsg-1ubuntu1, 2025.12+dfsg-2ubuntu1, 2025.12+dfsg-3ubuntu1, 2025.12+dfsg-4ubuntu1, 2026.05+dfsg-3ubuntu2, 2026.05+dfsg-4ubuntu1, 2026.05.1+dfsg-1ubuntu1, 2026.05.1+git20261001+dfsg-1ubuntu1
- Fixed versions
- Not specified
- CVEs
- CVE-2026-109399
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 02:54 UTC · Revision 1
Source evidence
SWUpdate through 2026.05.1 contains an improper certificate validation vulnerability in crypto/swupdate_cms_verify_openssl.c that trusts untrusted X.509 certificates embedded in CMS SignedData for chain building. Attackers holding a signing key from a sibling intermediate under the same root can embed that intermediate in the signature to install malicious updates.
osv:UBUNTU-CVE-2026-109399
swupdate
Fixed versions: Not specified
swupdate
Fixed versions: Not specified
swupdate
Fixed versions: Not specified
swupdate
Fixed versions: Not specified
Complete source record
{
"id": "dc6e148f5ddc352c97f802ad3b01427f37c6ccb215740029b328eb9c2b933450",
"url": "https://osv.dev/vulnerability/UBUNTU-CVE-2026-109399",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "UBUNTU-CVE-2026-109399",
"summary": "SWUpdate through 2026.05.1 contains an improper certificate validation vulnerability in crypto/swupdate_cms_verify_openssl.c that trusts untrusted X.509 certificates embedded in CMS SignedData for chain building. Attackers holding a signing key from a sibling intermediate under the same root can embed that intermediate in the signature to install malicious updates.",
"evidence": "osv:UBUNTU-CVE-2026-109399",
"products": [
{
"name": {
"value": "swupdate",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "2020.11-2",
"evidence": "/affected/0/versions"
},
{
"value": "2021.04-1.1",
"evidence": "/affected/0/versions"
},
{
"value": "2021.04-2",
"evidence": "/affected/0/versions"
},
{
"value": "2021.04-2build1",
"evidence": "/affected/0/versions"
},
{
"value": "2021.11-1",
"evidence": "/affected/0/versions"
}
]
},
{
"name": {
"value": "swupdate",
"evidence": "/affected/1/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "2023.05+dfsg-3",
"evidence": "/affected/1/versions"
},
{
"value": "2023.05+dfsg-4",
"evidence": "/affected/1/versions"
},
{
"value": "2023.05+dfsg-4build1",
"evidence": "/affected/1/versions"
},
{
"value": "2023.05+dfsg-5",
"evidence": "/affected/1/versions"
},
{
"value": "2023.12+dfsg-1",
"evidence": "/affected/1/versions"
},
{
"value": "2023.12.1+dfsg-1ubuntu1",
"evidence": "/affected/1/versions"
},
{
"value": "2023.12.1+dfsg-1ubuntu4",
"evidence": "/affected/1/versions"
},
{
"value": "2023.12.1+dfsg-1ubuntu5",
"evidence": "/affected/1/versions"
}
]
},
{
"name": {
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"evidence": "/affected/2/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "2025.12+dfsg-4ubuntu1",
"evidence": "/affected/2/versions"
},
{
"value": "2026.05+dfsg-3ubuntu2",
"evidence": "/affected/2/versions"
},
{
"value": "2026.05+dfsg-4ubuntu1",
"evidence": "/affected/2/versions"
},
{
"value": "2026.05.1+dfsg-1ubuntu1",
"evidence": "/affected/2/versions"
},
{
"value": "2026.05.1+git20261001+dfsg-1ubuntu1",
"evidence": "/affected/2/versions"
}
]
},
{
"name": {
"value": "swupdate",
"evidence": "/affected/3/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "2025.05+dfsg-2ubuntu1",
"evidence": "/affected/3/versions"
},
{
"value": "2025.05+dfsg-3ubuntu1",
"evidence": "/affected/3/versions"
},
{
"value": "2025.12+dfsg-1ubuntu1",
"evidence": "/affected/3/versions"
},
{
"value": "2025.12+dfsg-2ubuntu1",
"evidence": "/affected/3/versions"
},
{
"value": "2025.12+dfsg-3ubuntu1",
"evidence": "/affected/3/versions"
},
{
"value": "2025.12+dfsg-4ubuntu1",
"evidence": "/affected/3/versions"
}
]
}
],
"severity": "critical",
"structured": {
"id": "UBUNTU-CVE-2026-109399",
"aliases": [
"UBUNTU-CVE-2026-109399"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H"
},
{
"type": "CVSS_V4",
"score": "CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N"
},
{
"type": "Ubuntu",
"score": "medium"
}
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "swupdate",
"purl": "pkg:deb/ubuntu/swupdate?arch=source&distro=jammy",
"ecosystem": "Ubuntu:22.04:LTS"
},
"versions": [
"2020.11-2",
"2021.04-1.1",
"2021.04-2",
"2021.04-2build1",
"2021.11-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-109399.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libswupdate0.1",
"binary_version": "2021.11-1"
},
{
"binary_name": "lua-swupdate",
"binary_version": "2021.11-1"
},
{
"binary_name": "swupdate",
"binary_version": "2021.11-1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "swupdate",
"purl": "pkg:deb/ubuntu/swupdate?arch=source&distro=noble",
"ecosystem": "Ubuntu:24.04:LTS"
},
"versions": [
"2023.05+dfsg-3",
"2023.05+dfsg-4",
"2023.05+dfsg-4build1",
"2023.05+dfsg-5",
"2023.12+dfsg-1",
"2023.12.1+dfsg-1ubuntu1",
"2023.12.1+dfsg-1ubuntu4",
"2023.12.1+dfsg-1ubuntu5"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-109399.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libswupdate0.1",
"binary_version": "2023.12.1+dfsg-1ubuntu5"
},
{
"binary_name": "lua-swupdate",
"binary_version": "2023.12.1+dfsg-1ubuntu5"
},
{
"binary_name": "swupdate",
"binary_version": "2023.12.1+dfsg-1ubuntu5"
},
{
"binary_name": "swupdate-www",
"binary_version": "2023.12.1+dfsg-1ubuntu5"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
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}
],
"package": {
"name": "swupdate",
"purl": "pkg:deb/ubuntu/swupdate?arch=source&distro=stonking",
"ecosystem": "Ubuntu:26.10"
},
"versions": [
"2025.12+dfsg-4ubuntu1",
"2026.05+dfsg-3ubuntu2",
"2026.05+dfsg-4ubuntu1",
"2026.05.1+dfsg-1ubuntu1",
"2026.05.1+git20261001+dfsg-1ubuntu1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-109399.json"
},
"ecosystem_specific": {
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{
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},
{
"binary_name": "lua-swupdate",
"binary_version": "2026.05.1+git20261001+dfsg-1ubuntu1"
},
{
"binary_name": "swupdate",
"binary_version": "2026.05.1+git20261001+dfsg-1ubuntu1"
},
{
"binary_name": "swupdate-www",
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}
]
}
},
{
"ranges": [
{
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"package": {
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"purl": "pkg:deb/ubuntu/swupdate?arch=source&distro=resolute",
"ecosystem": "Ubuntu:26.04:LTS"
},
"versions": [
"2025.05+dfsg-2ubuntu1",
"2025.05+dfsg-3ubuntu1",
"2025.12+dfsg-1ubuntu1",
"2025.12+dfsg-2ubuntu1",
"2025.12+dfsg-3ubuntu1",
"2025.12+dfsg-4ubuntu1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-109399.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libswupdate0.1",
"binary_version": "2025.12+dfsg-4ubuntu1"
},
{
"binary_name": "lua-swupdate",
"binary_version": "2025.12+dfsg-4ubuntu1"
},
{
"binary_name": "swupdate",
"binary_version": "2025.12+dfsg-4ubuntu1"
},
{
"binary_name": "swupdate-www",
"binary_version": "2025.12+dfsg-4ubuntu1"
}
]
}
}
],
"modified": "2026-10-17T12:59:49.369275356Z",
"provider": "osv",
"upstream": [
"CVE-2026-109399"
],
"references": [
"https://ubuntu.com/security/CVE-2026-109399",
"https://www.cve.org/CVERecord?id=CVE-2026-109399",
"https://github.com/sbabic/swupdate",
"https://github.com/sbabic/swupdate/blob/2026.05.1/crypto/swupdate_cms_verify_openssl.c",
"https://github.com/sbabic/swupdate/commit/e66c5640664a31668926a24c0c84b6b6570dc0d9",
"https://groups.google.com/g/swupdate/c/dsoMcGFnEns",
"https://www.vulncheck.com/advisories/swupdate-through-2026.05.1-cms-signature-verification-bypass-via-embedded-intermediates"
]
},
"related_cves": [
{
"value": "CVE-2026-109399",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/1/score"
},
"source_id": "core-osv",
"document_id": 359806,
"published_at": "2026-10-12T16:17:00+00:00"
}