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CVE-2021-28697· NVD / CVE Program· CNA XEN

grant table v2 status pages may remain accessible after de-allocation Guest get permitted access to certain Xen-owned pages of memory.

Noroxi assessment

Priority: Monitor (action score 31/100)

  • 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: 0.26% (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) 4.13.3-r2; xen (Alpine:v3.13) 4.14.2-r0; xen (Alpine:v3.14) 4.15.0-r2.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to xen (Alpine:v3.11) 4.13.3-r2; xen (Alpine:v3.13) 4.14.2-r0; xen (Alpine:v3.14) 4.15.0-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

grant table v2 status pages may remain accessible after de-allocation Guest get permitted access to certain Xen-owned pages of memory. The majority of such pages remain allocated / associated with a guest for its entire lifetime. Grant table v2 status pages, however, get de-allocated when a guest switched (back) from v2 to v1. The freeing of such pages requires that the hypervisor know where in the guest these pages were mapped. The hypervisor tracks only one use within guest space, but racing requests from the guest to insert mappings of these pages may result in any of them to become mapped in multiple locations. Upon switching back from v2 to v1, the guest would then retain access to a page that was freed and perhaps re-used for other purposes.

HighCVSS 7.8 · v3.1—No exploit Fix available
Published
Aug 27, 2021
Updated
Jun 16, 2026
EPSS
0.2% · 17th percentile

Report tools

JSON

Action score

31

Monitor

Low priority for now.

CVSS
31 / 40 · 7.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.2%

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-2021-28697

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
debiandebian linux

Affected versions

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

  • debian debian linux11.0
  • fedoraproject fedora33
  • fedoraproject fedora34
  • fedoraproject fedora35
  • xen xen4.0.0 and later · up to 4.15.0 inclusive

Versions reported by the vendor

Affected version ranges reported by the assigning authority (XEN). Independent of NVD's CPE analysis and usually ahead of it.

  • Xen xen

    • xen-unstable, 4.15.xaffected
    • unspecified and later · before 4.12unknown
    • 4.13.x and later · before unspecifiedaffected
    • next of 4.14.x and later · before unspecifiednot affected
    • unspecified and later · before 4.12unknown
    • 4.11.x and later · before unspecifiedaffected
    • next of 4.12.x and later · before unspecifiednot affected

Package-level exposure

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

EcosystemPackageAffected rangeFix
Alpine:v3.11xenfrom 4.0.0 · before 4.13.3-r24.13.3-r2
Alpine:v3.13xenfrom 4.0.0 · before 4.14.2-r04.14.2-r0
Alpine:v3.14xenfrom 4.0.0 · before 4.15.0-r24.15.0-r2
Debian:11xenbefore 4.14.3-1~deb11u14.14.3-1~deb11u1
Debian:12xenbefore 4.14.3-14.14.3-1
openSUSE:Leap 15.2xenbefore 4.13.3_02-lp152.2.27.14.13.3_02-lp152.2.27.1
openSUSE:Leap 15.3xenbefore 4.14.2_04-3.9.14.14.2_04-3.9.1
SUSE:HPE Helion OpenStack 8xenbefore 4.9.4_20-3.91.14.9.4_20-3.91.1
SUSE:Linux Enterprise High Performance Computing 15 SP1-ESPOSxenbefore 4.12.4_12-3.52.14.12.4_12-3.52.1
SUSE:Linux Enterprise High Performance Computing 15-ESPOSxenbefore 4.10.4_26-3.61.14.10.4_26-3.61.1
SUSE:Linux Enterprise Module for Basesystem 15 SP2xenbefore 4.13.3_02-3.34.14.13.3_02-3.34.1
SUSE:Linux Enterprise Module for Basesystem 15 SP3xenbefore 4.14.2_04-3.9.14.14.2_04-3.9.1
SUSE:Linux Enterprise Server 11 SP4-LTSSxenbefore 4.4.4_50-61.67.14.4.4_50-61.67.1
SUSE:Linux Enterprise Server 12 SP2-BCLxenbefore 4.7.6_16-43.79.54.7.6_16-43.79.5
SUSE:Linux Enterprise Software Development Kit 12 SP5xenbefore 4.12.4_12-3.49.14.12.4_12-3.49.1
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-2021-28695Aug 27, 2021 · IOMMU page mapping issues on x86 T[his CNA information record relates to multiple CVEs; the text explains which aspects/vulnerabilities corr
    27Monitor
  • ← EarlierCVE-2021-28696Aug 27, 2021 · IOMMU page mapping issues on x86 T[his CNA information record relates to multiple CVEs; the text explains which aspects/vulnerabilities corr
    27Monitor
  • Later →CVE-2021-28698Aug 27, 2021 · long running loops in grant table handling In order to properly monitor resource use, Xen maintains information on the grant mappings a doma
    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:xen4.13.3-r2 · Alpine:v3.11Package registry (OSV)
debian:xen4.14.3-1 · Debian:12Package registry (OSV)
opensuse:xen4.13.3_02-lp152.2.27.1 · openSUSE:Leap 15.2Package registry (OSV)
suse:xen4.4.4_50-61.67.1 · SUSE:Linux Enterprise Server 11 SP4-LTSSPackage 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.

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).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

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

Weakness class (CWE)

CWE-362 · Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

CVSS vector

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

ATT&CK techniques

—

Change log

  1. Fix✗ → ✓

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

References

Show all references (5 more)

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

All records