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NVD / CVE Program· CNA mitre

CVE-2021-3308: An issue was discovered in Xen 4.12.3 through 4.12.4 and 4.13.1 through 4.14.x.

Noroxi assessment

Priority: Monitor (action score 22/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.41% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: xen (Alpine:v3.11) 4.13.2-r4; xen (Alpine:v3.13) 4.14.1-r1; xen (Alpine:v3.14) 4.14.1-r2.

Low priority for now. Upgrade to xen (Alpine:v3.11) 4.13.2-r4; xen (Alpine:v3.13) 4.14.1-r1; xen (Alpine:v3.14) 4.14.1-r2 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

MediumCVSS 5.5 · v3.1—No exploit Fix available
Published
Jan 26, 2021
Updated
Jun 17, 2026
EPSS
0.4% · 35th percentile
CWE
—

Report tools

JSON

Action score

22

Monitor

Low priority for now.

CVSS
22 / 40 · 5.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.4%

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2021-3308

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
xenxen
fedoraprojectfedora

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • fedoraproject fedora32
  • xen xen4.13.1 and later · up to 4.14.1 inclusive
  • xen xen4.12.3
  • xen xen4.12.4

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Alpine:v3.11xenfrom 4.13.1 · before 4.13.2-r44.13.2-r4
Alpine:v3.13xenfrom 4.13.1 · before 4.14.1-r14.14.1-r1
Alpine:v3.14xenfrom 4.13.1 · before 4.14.1-r24.14.1-r2
Debian:12xenbefore 4.14.1+11-gb0b734a8b3-14.14.1+11-gb0b734a8b3-1
SUSE:Linux Enterprise High Performance Computing 15 SP1-ESPOSxenbefore 4.12.4_08-3.43.34.12.4_08-3.43.3
SUSE:Linux Enterprise Module for Basesystem 15 SP2xenbefore 4.13.2_08-3.25.34.13.2_08-3.25.3
SUSE:Linux Enterprise Software Development Kit 12 SP5xenbefore 4.12.4_09-3.39.34.12.4_09-3.39.3
SUSE:OpenStack Cloud 9xenbefore 4.11.4_20-2.60.14.11.4_20-2.60.1

Same product

xen: all records

Other highest-scoring records for the same primary product.

  • CVE-2017-10921The grant-table feature in Xen through 4.8.x does not ensure sufficient type counts for a GNTMAP_device_map and GNTMAP_host_map mapping, whi
    41Plan
  • CVE-2017-10920The grant-table feature in Xen through 4.8.x mishandles a GNTMAP_device_map and GNTMAP_host_map mapping, when followed by only a GNTMAP_host
    41Plan
  • CVE-2017-10918Xen through 4.8.x does not validate memory allocations during certain P2M operations, which allows guest OS users to obtain privileged host
    41Plan

Published before and after this one in the same product

  • ← EarlierCVE-2020-29485Dec 15, 2020 · An issue was discovered in Xen 4.6 through 4.14.x.
    22Monitor
  • ← EarlierCVE-2020-29486Dec 15, 2020 · An issue was discovered in Xen through 4.14.x.
    24Monitor
  • Later →CVE-2021-26933Feb 16, 2021 · An issue was discovered in Xen 4.9 through 4.14.x.
    22Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
alpine:xen4.13.2-r4 · Alpine:v3.11Package registry (OSV)
debian:xen4.14.1+11-gb0b734a8b3-1 · Debian:12Package registry (OSV)
suse:xen4.12.4_09-3.39.3 · SUSE:Linux Enterprise Software Development Kit 12 SP5Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

—

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (3 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records