An issue was discovered in Xen 4.12.3 through 4.12.4 and 4.13.1 through 4.14.x.
Key facts
- Attack vector
- Local
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- No fix listed
Attack profile from CVSS 3.1 · NVD. Fix status from CNA.
Summary
An issue was discovered in Xen 4.12.3 through 4.12.4 and 4.13.1 through 4.14.x. An x86 HVM guest with PCI pass through devices can force the allocation of all IDT vectors on the system by rebooting itself with MSI or MSI-X capabilities enabled and entries setup. Such reboots will leak any vectors used by the MSI(-X) entries that the guest might had enabled, and hence will lead to vector exhaustion on the system, not allowing further PCI pass through devices to work properly. HVM guests with PCI pass through devices can mount a Denial of Service (DoS) attack affecting the pass through of PCI devices to other guests or the hardware domain. In the latter case, this would affect the entire host.
Why it matters now
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| — | — | all versions | — | No fix listed | CNA |
- — Vendor— Affected all versions Fixed in — No fix listed CNA
CPE configurations NVD · 4
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:o:xen:xen:*:*:*:*:*:*:*:* | 4.13.1 – 4.14.1 | Vulnerable | Xen |
| cpe:2.3:o:xen:xen:4.12.3:*:*:*:*:*:*:* | 4.12.3 | Vulnerable | Xen |
| cpe:2.3:o:xen:xen:4.12.4:*:*:*:*:*:*:* | 4.12.4 | Vulnerable | Xen |
| cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:* | 32 | Vulnerable | Fedoraproject |
- cpe:2.3:o:xen:xen:*:*:*:*:*:*:*:* Versions 4.13.1 – 4.14.1 Vulnerable ·Xen
- cpe:2.3:o:xen:xen:4.12.3:*:*:*:*:*:*:* Versions 4.12.3 Vulnerable ·Xen
- cpe:2.3:o:xen:xen:4.12.4:*:*:*:*:*:*:* Versions 4.12.4 Vulnerable ·Xen
- cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:* Versions 32 Vulnerable ·Fedoraproject
Remediation
No fixed version listed by the sources yet.
Vendor assessments
Timeline
- 2026-10-02 Threatist record created from CVE-2021-3308
- 2026-10-03 Alias added: GHSA-4gx5-7c23-79mh
References
Sources
- CVE-2021-3308 · CVE Program
- CVE-2021-3308 · NVD
- FIRST EPSS
- GHSA-4gx5-7c23-79mh · GitHub Advisory Database · CC BY 4.0
- CVE-2021-3308 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences