xen — security advisory
An issue was discovered in Xen through 4.14.x. There are missing memory barriers when accessing/allocating an event channel. Event channels control structures can be accessed lockless as long as the port is considered to be valid. Such a sequence is missing an appropriate memory barrier (e.g., smp_*mb()) to prevent both the compiler and CPU from re-ordering access. A malicious guest may be able to cause a hypervisor crash resulting in a Denial of Service (DoS). Information leak and privilege escalation cannot be excluded. Systems running all versions of Xen are affected. Whether a system is vulnerable will depend on the CPU and compiler used to build Xen. For all systems, the presence and the scope of the vulnerability depend on the precise re-ordering performed by the compiler used to build Xen. We have not been able to survey compilers; consequently we cannot say which compiler(s) might produce vulnerable code (with which code generation options). GCC documentation clearly suggests that re-ordering is possible. Arm systems will also be vulnerable if the CPU is able to re-order memory access. Please consult your CPU vendor. x86 systems are only vulnerable if a compiler performs re-ordering.
- Products
- xen
- Affected versions
- Not specified
- Fixed versions
- 4.11.4-r2, 4.12.3-r4, 4.13.1-r4, 4.14.0-r1
- CVEs
- CVE-2020-25603
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 1 Nov 2026, 12:07 UTC · Revision 1
Source evidence
An issue was discovered in Xen through 4.14.x. There are missing memory barriers when accessing/allocating an event channel. Event channels control structures can be accessed lockless as long as the port is considered to be valid. Such a sequence is missing an appropriate memory barrier (e.g., smp_*mb()) to prevent both the compiler and CPU from re-ordering access. A malicious guest may be able to cause a hypervisor crash resulting in a Denial of Service (DoS). Information leak and privilege escalation cannot be excluded. Systems running all versions of Xen are affected. Whether a system is vulnerable will depend on the CPU and compiler used to build Xen. For all systems, the presence and the scope of the vulnerability depend on the precise re-ordering performed by the compiler used to build Xen. We have not been able to survey compilers; consequently we cannot say which compiler(s) might produce vulnerable code (with which code generation options). GCC documentation clearly suggests that re-ordering is possible. Arm systems will also be vulnerable if the CPU is able to re-order memory access. Please consult your CPU vendor. x86 systems are only vulnerable if a compiler performs re-ordering.
osv:ALPINE-CVE-2020-25603
xen
Fixed versions: 4.12.3-r4
xen
Fixed versions: 4.13.1-r4
xen
Fixed versions: 4.13.1-r4
xen
Fixed versions: 4.14.0-r1
xen
Fixed versions: 4.14.0-r1
xen
Fixed versions: 4.14.0-r1
xen
Fixed versions: 4.14.0-r1
xen
Fixed versions: 4.14.0-r1
xen
Fixed versions: 4.14.0-r1
xen
Fixed versions: 4.14.0-r1
xen
Fixed versions: 4.14.0-r1
xen
Fixed versions: 4.14.0-r1
xen
Fixed versions: 4.14.0-r1
xen
Fixed versions: 4.14.0-r1
xen
Fixed versions: 4.14.0-r1
xen
Fixed versions: 4.11.4-r2
Complete source record
{
"id": "e7a01f91bdd9824aff32066f6499ed6bf52c8572df517c03aea32de36dd93d45",
"url": "https://osv.dev/vulnerability/ALPINE-CVE-2020-25603",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "ALPINE-CVE-2020-25603",
"summary": "An issue was discovered in Xen through 4.14.x. There are missing memory barriers when accessing/allocating an event channel. Event channels control structures can be accessed lockless as long as the port is considered to be valid. Such a sequence is missing an appropriate memory barrier (e.g., smp_*mb()) to prevent both the compiler and CPU from re-ordering access. A malicious guest may be able to cause a hypervisor crash resulting in a Denial of Service (DoS). Information leak and privilege escalation cannot be excluded. Systems running all versions of Xen are affected. Whether a system is vulnerable will depend on the CPU and compiler used to build Xen. For all systems, the presence and the scope of the vulnerability depend on the precise re-ordering performed by the compiler used to build Xen. We have not been able to survey compilers; consequently we cannot say which compiler(s) might produce vulnerable code (with which code generation options). GCC documentation clearly suggests that re-ordering is possible. Arm systems will also be vulnerable if the CPU is able to re-order memory access. Please consult your CPU vendor. x86 systems are only vulnerable if a compiler performs re-ordering.",
"evidence": "osv:ALPINE-CVE-2020-25603",
"products": [
{
"name": {
"value": "xen",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "4.12.3-r4",
"evidence": "/affected/0/ranges"
}
],
"affected_versions": []
},
{
"name": {
"value": "xen",
"evidence": "/affected/1/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "4.13.1-r4",
"evidence": "/affected/1/ranges"
}
],
"affected_versions": []
},
{
"name": {
"value": "xen",
"evidence": "/affected/2/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "4.13.1-r4",
"evidence": "/affected/2/ranges"
}
],
"affected_versions": []
},
{
"name": {
"value": "xen",
"evidence": "/affected/3/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "4.14.0-r1",
"evidence": "/affected/3/ranges"
}
],
"affected_versions": []
},
{
"name": {
"value": "xen",
"evidence": "/affected/4/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "4.14.0-r1",
"evidence": "/affected/4/ranges"
}
],
"affected_versions": []
},
{
"name": {
"value": "xen",
"evidence": "/affected/5/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "4.14.0-r1",
"evidence": "/affected/5/ranges"
}
],
"affected_versions": []
},
{
"name": {
"value": "xen",
"evidence": "/affected/6/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "4.14.0-r1",
"evidence": "/affected/6/ranges"
}
],
"affected_versions": []
},
{
"name": {
"value": "xen",
"evidence": "/affected/7/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "4.14.0-r1",
"evidence": "/affected/7/ranges"
}
],
"affected_versions": []
},
{
"name": {
"value": "xen",
"evidence": "/affected/8/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "4.14.0-r1",
"evidence": "/affected/8/ranges"
}
],
"affected_versions": []
},
{
"name": {
"value": "xen",
"evidence": "/affected/9/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "4.14.0-r1",
"evidence": "/affected/9/ranges"
}
],
"affected_versions": []
},
{
"name": {
"value": "xen",
"evidence": "/affected/10/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "4.14.0-r1",
"evidence": "/affected/10/ranges"
}
],
"affected_versions": []
},
{
"name": {
"value": "xen",
"evidence": "/affected/11/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "4.14.0-r1",
"evidence": "/affected/11/ranges"
}
],
"affected_versions": []
},
{
"name": {
"value": "xen",
"evidence": "/affected/12/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "4.14.0-r1",
"evidence": "/affected/12/ranges"
}
],
"affected_versions": []
},
{
"name": {
"value": "xen",
"evidence": "/affected/13/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "4.14.0-r1",
"evidence": "/affected/13/ranges"
}
],
"affected_versions": []
},
{
"name": {
"value": "xen",
"evidence": "/affected/14/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "4.14.0-r1",
"evidence": "/affected/14/ranges"
}
],
"affected_versions": []
},
{
"name": {
"value": "xen",
"evidence": "/affected/15/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "4.11.4-r2",
"evidence": "/affected/15/ranges"
}
],
"affected_versions": []
}
],
"severity": "high",
"structured": {
"id": "ALPINE-CVE-2020-25603",
"aliases": [
"ALPINE-CVE-2020-25603"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
}
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "4.12.3-r4"
}
]
}
],
"package": {
"name": "xen",
"purl": "pkg:apk/alpine/xen?arch=source",
"ecosystem": "Alpine:v3.10"
},
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-CVE-2020-25603.json"
},
"ecosystem_specific": {}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "4.13.1-r4"
}
]
}
],
"package": {
"name": "xen",
"purl": "pkg:apk/alpine/xen?arch=source",
"ecosystem": "Alpine:v3.11"
},
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-CVE-2020-25603.json"
},
"ecosystem_specific": {}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "4.13.1-r4"
}
]
}
],
"package": {
"name": "xen",
"purl": "pkg:apk/alpine/xen?arch=source",
"ecosystem": "Alpine:v3.12"
},
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-CVE-2020-25603.json"
},
"ecosystem_specific": {}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "4.14.0-r1"
}
]
}
],
"package": {
"name": "xen",
"purl": "pkg:apk/alpine/xen?arch=source",
"ecosystem": "Alpine:v3.13"
},
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-CVE-2020-25603.json"
},
"ecosystem_specific": {}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "4.14.0-r1"
}
]
}
],
"package": {
"name": "xen",
"purl": "pkg:apk/alpine/xen?arch=source",
"ecosystem": "Alpine:v3.14"
},
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-CVE-2020-25603.json"
},
"ecosystem_specific": {}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "4.14.0-r1"
}
]
}
],
"package": {
"name": "xen",
"purl": "pkg:apk/alpine/xen?arch=source",
"ecosystem": "Alpine:v3.15"
},
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-CVE-2020-25603.json"
},
"ecosystem_specific": {}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "4.14.0-r1"
}
]
}
],
"package": {
"name": "xen",
"purl": "pkg:apk/alpine/xen?arch=source",
"ecosystem": "Alpine:v3.16"
},
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-CVE-2020-25603.json"
},
"ecosystem_specific": {}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "4.14.0-r1"
}
]
}
],
"package": {
"name": "xen",
"purl": "pkg:apk/alpine/xen?arch=source",
"ecosystem": "Alpine:v3.17"
},
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-CVE-2020-25603.json"
},
"ecosystem_specific": {}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "4.14.0-r1"
}
]
}
],
"package": {
"name": "xen",
"purl": "pkg:apk/alpine/xen?arch=source",
"ecosystem": "Alpine:v3.18"
},
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-CVE-2020-25603.json"
},
"ecosystem_specific": {}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "4.14.0-r1"
}
]
}
],
"package": {
"name": "xen",
"purl": "pkg:apk/alpine/xen?arch=source",
"ecosystem": "Alpine:v3.19"
},
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-CVE-2020-25603.json"
},
"ecosystem_specific": {}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "4.14.0-r1"
}
]
}
],
"package": {
"name": "xen",
"purl": "pkg:apk/alpine/xen?arch=source",
"ecosystem": "Alpine:v3.20"
},
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-CVE-2020-25603.json"
},
"ecosystem_specific": {}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "4.14.0-r1"
}
]
}
],
"package": {
"name": "xen",
"purl": "pkg:apk/alpine/xen?arch=source",
"ecosystem": "Alpine:v3.21"
},
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-CVE-2020-25603.json"
},
"ecosystem_specific": {}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "4.14.0-r1"
}
]
}
],
"package": {
"name": "xen",
"purl": "pkg:apk/alpine/xen?arch=source",
"ecosystem": "Alpine:v3.22"
},
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-CVE-2020-25603.json"
},
"ecosystem_specific": {}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "4.14.0-r1"
}
]
}
],
"package": {
"name": "xen",
"purl": "pkg:apk/alpine/xen?arch=source",
"ecosystem": "Alpine:v3.23"
},
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-CVE-2020-25603.json"
},
"ecosystem_specific": {}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "4.14.0-r1"
}
]
}
],
"package": {
"name": "xen",
"purl": "pkg:apk/alpine/xen?arch=source",
"ecosystem": "Alpine:v3.24"
},
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-CVE-2020-25603.json"
},
"ecosystem_specific": {}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "4.11.4-r2"
}
]
}
],
"package": {
"name": "xen",
"purl": "pkg:apk/alpine/xen?arch=source",
"ecosystem": "Alpine:v3.9"
},
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-CVE-2020-25603.json"
},
"ecosystem_specific": {}
}
],
"modified": "2026-10-26T11:17:55.153972272Z",
"provider": "osv",
"upstream": [
"CVE-2020-25603"
],
"references": [
"https://security.alpinelinux.org/vuln/CVE-2020-25603"
]
},
"related_cves": [
{
"value": "CVE-2020-25603",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 450538,
"published_at": "2020-09-23T22:15:13.853+00:00"
}