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Fencer Intel
medium 5.5

CVE-2021-28699 json

inadequate grant-v2 status frames array bounds check The v2 grant table interface separates grant attributes from grant status.

published 5y ago modified 4mo ago also EUVD-2021-15356

cvss
5.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 29%
public exploits
0
none known

Summary

inadequate grant-v2 status frames array bounds check The v2 grant table interface separates grant attributes from grant status. That is, when operating in this mode, a guest has two tables. As a result, guests also need to be able to retrieve the addresses that the new status tracking table can be accessed through. For 32-bit guests on x86, translation of requests has to occur because the interface structure layouts commonly differ between 32- and 64-bit. The translation of the request to obtain the frame numbers of the grant status table involves translating the resulting array of frame numbers. Since the space used to carry out the translation is limited, the translation layer tells the core function the capacity of the array within translation space. Unfortunately the core function then only enforces array bounds to be below 8 times the specified value, and would write past the available space if enough frame numbers needed storing.

Patch / fix

  • xen Debian 14, Debian 13, Debian 12 4.14.3-1

debian advisories DEBIAN-CVE-2021-28699

  • xen SLES for SAP 12 SP3, SLES 12 SP3-LTSS, SLES 12 SP3-BCL +3 more 4.9.4_20-3.91.1
  • xen SLES for SAP 12 SP4, SLES 12 SP4-LTSS, OpenStack Cloud Crowbar 9 +1 more 4.11.4_20-2.60.1
  • xen SLES for SAP 15, SLE High Performance Computing 15-LTSS, SLE High Performance Computing 15-ESPOS 4.10.4_26-3.61.1
  • xen SLES for SAP 15 SP1, SLES 15 SP1-LTSS, SLES 15 SP1-BCL +6 more 4.12.4_12-3.52.1
  • xen SLES for SAP 12 SP5, SLES 12 SP5, SLE Software Development Kit 12 SP5 4.12.4_12-3.49.1
  • xen SLE Module for Server Applications 15 SP3, SLE Module for Basesystem 15 SP3 4.14.2_04-3.9.1
  • xen SLE Module for Server Applications 15 SP2, SLE Module for Basesystem 15 SP2, SLE Micro 5.0 4.13.3_02-3.34.1

suse advisories SUSE-SU-2021:2957-1SUSE-SU-2021:2955-1SUSE-SU-2021:2943-1SUSE-SU-2021:2925-1SUSE-SU-2021:2924-1SUSE-SU-2021:2923-1

  • xen openSUSE Leap 15.2 4.13.3_02-lp152.2.27.1
  • xen openSUSE Leap 15.3 4.14.2_04-3.9.1

opensuse advisories openSUSE-SU-2021:1236-1openSUSE-SU-2021:2923-1

  • xen Alpine 3.12, Alpine 3.11 4.13.3-r2
  • xen Alpine 3.13 4.14.2-r0
  • xen Alpine 3.24, Alpine 3.23, Alpine 3.22 +8 more 4.15.0-r2

alpine advisories ALPINE-CVE-2021-28699

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Is CVE-2021-28699 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-28699 updated cvss 6.8

xen: malicious guest kernel leads to DoS

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

0.35% chance of exploitation in the next 30 days, higher than 29% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
NVD 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 4.9 AV:L/AC:L/Au:N/C:N/I:N/A:C

Affected products

  • Xen xen

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.