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CVE-2021-3308

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...

5.5 MediumFix available

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.

Attack profile

How easy it is to exploit

Attack vector
Local
Complexity
Low
Privileges needed
Low
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
None
Availability
High

Exploit likelihood

0.42%Down 0.6 points since Apr 14, 2021
90%50%10%1%

What each source reports

NVD Score used 5.5

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.

Record
CVE-2021-3308
CVSS 3.1
5.5 MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CVSS 2.0
4.9 MediumAV:L/AC:L/Au:N/C:N/I:N/A:C
Updated
2026-11-02
CVE List No score

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.

Record
CVE-2021-3308
Updated
2026-11-02
EUVDEUVD-2021-26642 No score

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.

Record
EUVD-2021-26642
Updated
2026-11-03
GitHub AdvisoriesGHSA-4gx5-7c23-79mh 5.5

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...

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.

Record
GHSA-4gx5-7c23-79mh
CVSS 3.1
5.5 MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVALPINE-CVE-2021-3308 5.5

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.

Record
ALPINE-CVE-2021-3308
CVSS 3.1
5.5 MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSV 5.5

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.

Record
CVE-2021-3308
CVSS 3.1
5.5 MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
Show 6 moreShow less
OSVDEBIAN-CVE-2021-3308 5.5

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.

Record
DEBIAN-CVE-2021-3308
CVSS 3.1
5.5 MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVUBUNTU-CVE-2021-3308 5.5

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.

Record
UBUNTU-CVE-2021-3308
CVSS 3.1
5.5 MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVSUSE-SU-2021:1023-1 No score

Security update for xen

This update for xen fixes the following issues:

  • CVE-2021-3308: VUL-0: xen: IRQ vector leak on x86 (bsc#1181254, XSA-360)
  • CVE-2021-28687: VUL-0: xen: HVM soft-reset crashes toolstack (bsc#1183072, XSA-368)
  • CVE-2021-20257: VUL-0: xen: infinite loop issue in the e1000 NIC emulator (bsc#1182846)
  • CVE-2020-28368: VUL-0: xen: Intel RAPL sidechannel attack aka PLATYPUS attack aka (bsc#1178591, XSA-351)
  • L3: conring size for XEN HV's with huge memory to small. Inital Xen logs cut (bsc#1177204)
  • Kdump of HVM fails, soft-reset not handled by libxl (bsc#1179148)
  • OpenQA job causes libvirtd to dump core when running kdump inside domain (bsc#1181989)
  • Allow restart of xenwatchdogd, enable tuning of keep-alive interval and timeout options via XENWATCHDOGD_ARGS= (bsc#1178736)
  • The receiving side did detect holes in a to-be-allocated superpage, but allocated a superpage anyway. This resulted to over-allocation (bsc#1177112)
  • The receiving side may punch holes incorrectly into optimistically allocated superpages. Also reduce overhead in bitmap handling (bsc#1177112)
  • Upstream bug fixes (bsc#1027519)
Record
SUSE-SU-2021:1023-1
Updated
2026-11-02
OSVSUSE-SU-2021:1028-1 No score

Security update for xen

This update for xen fixes the following issues:

  • CVE-2021-3308: VUL-0: xen: IRQ vector leak on x86 (bsc#1181254, XSA-360)
  • CVE-2021-28687: HVM soft-reset crashes toolstack (bsc#1183072, XSA-368)
  • L3: conring size for XEN HV's with huge memory to small. Inital Xen logs cut (bsc#1177204)
  • L3: XEN domU crashed on resume when using the xl unpause command (bsc#1182576)
  • L3: xen: no needsreboot flag set (bsc#1180690)
  • kdump of HVM fails, soft-reset not handled by libxl (bsc#1179148)
  • openQA job causes libvirtd to dump core when running kdump inside domain (bsc#1181989)
  • Upstream bug fixes (bsc#1027519)
Record
SUSE-SU-2021:1028-1
Updated
2026-11-02
OSVSUSE-SU-2021:1460-1 No score

Security update for xen

This update for xen fixes the following issues:

  • CVE-2020-28368: Intel RAPL sidechannel attack aka PLATYPUS attack (bsc#1178591, XSA-351)
  • CVE-2021-3308: IRQ vector leak on x86 (bsc#1181254, XSA-360)
  • CVE-2021-28687: HVM soft-reset crashes toolstack (bsc#1183072, XSA-368)
  • L3: conring size for XEN HV's with huge memory to small (bsc#1177204).
  • kdump of HVM fails, soft-reset not handled by libxl (bsc#1179148)
  • openQA job causes libvirtd to dump core when running kdump inside domain (bsc#1181989).
  • Upstream bug fixes (bsc#1027519)
Record
SUSE-SU-2021:1460-1
Updated
2026-11-02
OSVSUSE-SU-2021:2955-1 No score

Security update for xen

This update for xen fixes the following issues:

Security issues fixed:

  • CVE-2021-28698: long running loops in grant table handling (XSA-380)(bsc#1189378).

  • CVE-2021-28697: grant table v2 status pages may remain accessible after de-allocation (XSA-379)(bsc#1189376).

  • CVE-2021-28694,CVE-2021-28695,CVE-2021-28696: IOMMU page mapping issues on x86 (XSA-378)(bsc#1189373).

  • CVE-2021-28699: inadequate grant-v2 status frames array bounds check (XSA-382)(bsc#1189380).

  • CVE-2021-28692: xen: inappropriate x86 IOMMU timeout detection / handling (bsc#1186429)

  • CVE-2021-28690: xen: x86: TSX Async Abort protections not restored after S3 (bsc#1186434)

  • CVE-2021-0089: xen: Speculative Code Store Bypass (bsc#1186433)

  • CVE-2021-20255: Fixed stack overflow via infinite recursion in eepro100 (bsc#1182654)

  • CVE-2021-3592: slirp: invalid pointer initialization may lead to information disclosure (bootp)(bsc#1187369).

  • CVE-2021-3594: slirp: invalid pointer initialization may lead to information disclosure (udp)(bsc#1187378).

  • CVE-2021-3595: slirp: invalid pointer initialization may lead to information disclosure (tftp)(bsc#1187376).

  • CVE-2021-3308: Fixed IRQ vector leak on x86 (XSA-360)(bsc#1181254).

  • Prevent superpage allocation in the LAPIC and ACPI_INFO range (bsc#1189882).

Record
SUSE-SU-2021:2955-1
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
xen
Alpine:v3.11
 4.13.1 up to 4.13.2-r4
4.13.2-r4
xen
Alpine:v3.12
 4.13.1 up to 4.13.2-r4
4.13.2-r4
xen
Alpine:v3.13
 4.13.1 up to 4.14.1-r1
4.14.1-r1
xen
Alpine:v3.14
 4.13.1 up to 4.14.1-r2
4.14.1-r2
xen
Alpine:v3.15
 4.13.1 up to 4.14.1-r2
4.14.1-r2
xen
Alpine:v3.16
 4.13.1 up to 4.14.1-r2
4.14.1-r2
xen
Alpine:v3.17
 4.13.1 up to 4.14.1-r2
4.14.1-r2
xen
Alpine:v3.18
 4.13.1 up to 4.14.1-r2
4.14.1-r2
xen
Alpine:v3.19
 4.13.1 up to 4.14.1-r2
4.14.1-r2
xen
Alpine:v3.20
 4.13.1 up to 4.14.1-r2
4.14.1-r2
Show 26 moreShow less
Affected packages
PackageAffectedFixed
xen
Alpine:v3.21
 4.13.1 up to 4.14.1-r2
4.14.1-r2
xen
Alpine:v3.22
 4.13.1 up to 4.14.1-r2
4.14.1-r2
xen
Alpine:v3.23
 4.13.1 up to 4.14.1-r2
4.14.1-r2
xen
Alpine:v3.24
 4.13.1 up to 4.14.1-r2
4.14.1-r2
xen
Debian:12
 before 4.14.1+11-gb0b734a8b3-1
4.14.1+11-gb0b734a8b3-1
xen
Debian:13
 before 4.14.1+11-gb0b734a8b3-1
4.14.1+11-gb0b734a8b3-1
xen
Debian:14
 before 4.14.1+11-gb0b734a8b3-1
4.14.1+11-gb0b734a8b3-1
xen
SUSE:Linux Enterprise Software Development Kit 12 SP5
From an advisory covering 4 CVEs
 before 4.12.4_09-3.39.3
4.12.4_09-3.39.3
xen
SUSE:Linux Enterprise Server 12 SP5
From an advisory covering 4 CVEs
 before 4.12.4_09-3.39.3
4.12.4_09-3.39.3
xen
SUSE:Linux Enterprise Server for SAP Applications 12 SP5
From an advisory covering 4 CVEs
 before 4.12.4_09-3.39.3
4.12.4_09-3.39.3
xen
SUSE:Linux Enterprise Module for Basesystem 15 SP2
From an advisory covering 2 CVEs
 before 4.13.2_08-3.25.3
4.13.2_08-3.25.3
xen
SUSE:Linux Enterprise Module for Server Applications 15 SP2
From an advisory covering 2 CVEs
 before 4.13.2_08-3.25.3
4.13.2_08-3.25.3
xen
SUSE:Linux Enterprise Micro 5.0
From an advisory covering 2 CVEs
 before 4.13.2_08-3.25.3
4.13.2_08-3.25.3
xen
SUSE:Linux Enterprise High Performance Computing 15 SP1-ESPOS
From an advisory covering 3 CVEs
 before 4.12.4_08-3.43.3
4.12.4_08-3.43.3
xen
SUSE:Linux Enterprise High Performance Computing 15 SP1-LTSS
From an advisory covering 3 CVEs
 before 4.12.4_08-3.43.3
4.12.4_08-3.43.3
xen
SUSE:Linux Enterprise Server 15 SP1-BCL
From an advisory covering 3 CVEs
 before 4.12.4_08-3.43.3
4.12.4_08-3.43.3
xen
SUSE:Linux Enterprise Server 15 SP1-LTSS
From an advisory covering 3 CVEs
 before 4.12.4_08-3.43.3
4.12.4_08-3.43.3
xen
SUSE:Linux Enterprise Server for SAP Applications 15 SP1
From an advisory covering 3 CVEs
 before 4.12.4_08-3.43.3
4.12.4_08-3.43.3
xen
SUSE:Manager Proxy 4.0
From an advisory covering 3 CVEs
 before 4.12.4_08-3.43.3
4.12.4_08-3.43.3
xen
SUSE:Manager Retail Branch Server 4.0
From an advisory covering 3 CVEs
 before 4.12.4_08-3.43.3
4.12.4_08-3.43.3
xen
SUSE:Manager Server 4.0
From an advisory covering 3 CVEs
 before 4.12.4_08-3.43.3
4.12.4_08-3.43.3
xen
SUSE:Enterprise Storage 6
From an advisory covering 3 CVEs
 before 4.12.4_08-3.43.3
4.12.4_08-3.43.3
xen
SUSE:OpenStack Cloud 9
From an advisory covering 14 CVEs
 before 4.11.4_20-2.60.1
4.11.4_20-2.60.1
xen
SUSE:OpenStack Cloud Crowbar 9
From an advisory covering 14 CVEs
 before 4.11.4_20-2.60.1
4.11.4_20-2.60.1
xen
SUSE:Linux Enterprise Server for SAP Applications 12 SP4
From an advisory covering 14 CVEs
 before 4.11.4_20-2.60.1
4.11.4_20-2.60.1
xen
SUSE:Linux Enterprise Server 12 SP4-LTSS
From an advisory covering 14 CVEs
 before 4.11.4_20-2.60.1
4.11.4_20-2.60.1

History

History
RecordedChangedSources
affected, facts
affected
aliasesEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2021-3308 is a medium vulnerability (CVSS 5.5) in Xen, published January 26, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.42%, the 36th percentile. Fixed in xen 4.13.2-r4.

References

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