ALPINE-CVE-2026-23553
In the context switch logic Xen attempts to skip an IBPB in the case of a vCPU returning to a CPU on which it was the previous vCPU to run. While safe for Xen's isolation between vCPUs, this prevents the guest kernel correctly isolating between tasks. Consider: 1) vCPU runs on CPU A, running task 1. 2) vCPU moves to CPU B, idle gets scheduled on A. Xen skips IBPB. 3) On CPU B, guest kernel switches from task 1 to 2, issuing IBPB. 4) vCPU moves back to CPU A. Xen skips IBPB again. Now, task 2 is running on CPU A with task 1's training still in the BTB.
ALPINE-CVE-2026-23553
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: osv:ALPINE-CVE-2026-23553
xen
Source reference: /affected/0/package/name
- Affected versions
- Not stated in this record
- Fixed versions
- 4.18.5-r4
Source reference:
/affected/0/ranges - Prerequisites
- Not stated in this record
xen
Source reference: /affected/1/package/name
- Affected versions
- Not stated in this record
- Fixed versions
- 4.19.4-r1
Source reference:
/affected/1/ranges - Prerequisites
- Not stated in this record
xen
Source reference: /affected/2/package/name
- Affected versions
- Not stated in this record
- Fixed versions
- 4.20.2-r1
Source reference:
/affected/2/ranges - Prerequisites
- Not stated in this record
xen
Source reference: /affected/3/package/name
- Affected versions
- Not stated in this record
- Fixed versions
- 4.20.2-r1
Source reference:
/affected/3/ranges - Prerequisites
- Not stated in this record
xen
Source reference: /affected/4/package/name
- Affected versions
- Not stated in this record
- Fixed versions
- 4.21.0-r2
Source reference:
/affected/4/ranges - Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "4.6.0"
},
{
"fixed": "4.18.5-r4"
}
]
}
],
"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-2026-23553.json"
},
"ecosystem_specific": {}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "4.6.0"
},
{
"fixed": "4.19.4-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-2026-23553.json"
},
"ecosystem_specific": {}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "4.6.0"
},
{
"fixed": "4.20.2-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-2026-23553.json"
},
"ecosystem_specific": {}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "4.6.0"
},
{
"fixed": "4.20.2-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-2026-23553.json"
},
"ecosystem_specific": {}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "4.6.0"
},
{
"fixed": "4.21.0-r2"
}
]
}
],
"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-2026-23553.json"
},
"ecosystem_specific": {}
}
]Publisher severity
No explicit severity was provided.
- Event
- #54177 · Revision 1
- Added to Heist Feed
- Publisher date