Alpine: xen: security update to 4.13.4-r2

high Tenable Cloud Security Plugin ID 407787

Description

There are packages installed that are affected by multiple vulnerabilities referenced in the following CVEs:

- PoD operations on misaligned GFNs T[his CNA information record relates to multiple CVEs; the text explains
which aspects/vulnerabilities correspond to which CVE.] x86 HVM and PVH guests may be started in populate-
on-demand (PoD) mode, to provide a way for them to later easily have more memory assigned. Guests are
permitted to control certain P2M aspects of individual pages via hypercalls. These hypercalls may act on
ranges of pages specified via page orders (resulting in a power-of-2 number of pages). The implementation
of some of these hypercalls for PoD does not enforce the base page frame number to be suitably aligned for
the specified order, yet some code involved in PoD handling actually makes such an assumption. These
operations are XENMEM_decrease_reservation (CVE-2021-28704) and XENMEM_populate_physmap (CVE-2021-28707),
the latter usable only by domains controlling the guest, i.e. a de-privileged qemu or a stub domain.
(Patch 1, combining the fix to both these two issues.) In addition handling of XENMEM_decrease_reservation
can also trigger a host crash when the specified page order is neither 4k nor 2M nor 1G (CVE-2021-28708,
patch 2). (CVE-2021-28704, CVE-2021-28707, CVE-2021-28708)

- issues with partially successful P2M updates on x86 T[his CNA information record relates to multiple CVEs;
the text explains which aspects/vulnerabilities correspond to which CVE.] x86 HVM and PVH guests may be
started in populate-on-demand (PoD) mode, to provide a way for them to later easily have more memory
assigned. Guests are permitted to control certain P2M aspects of individual pages via hypercalls. These
hypercalls may act on ranges of pages specified via page orders (resulting in a power-of-2 number of
pages). In some cases the hypervisor carries out the requests by splitting them into smaller chunks. Error
handling in certain PoD cases has been insufficient in that in particular partial success of some
operations was not properly accounted for. There are two code paths affected - page removal
(CVE-2021-28705) and insertion of new pages (CVE-2021-28709). (We provide one patch which combines the fix
to both issues.) (CVE-2021-28705)

- guests may exceed their designated memory limit When a guest is permitted to have close to 16TiB of
memory, it may be able to issue hypercalls to increase its memory allocation beyond the administrator
established limit. This is a result of a calculation done with 32-bit precision, which may overflow. It
would then only be the overflowed (and hence small) number which gets compared against the established
upper bound. (CVE-2021-28706)

Plugin Details

Severity: High

ID: 407787

Version: Revision 1.29

Type: Local

Family: Alpine Linux Local Security Checks

Published: 10/31/2023

Updated: 7/2/2026

Supported Sensors: Agentless Assessment, Tenable Cloud Security, Tenable Self-Hosted Container Security

Risk Information

VPR

Risk Factor: Medium

Score: 5

Percentile: 95.11

CVSS v2

Risk Factor: Medium

Base Score: 6.9

Temporal Score: 5.1

Vector: CVSS2#AV:L/AC:M/Au:N/C:C/I:C/A:C

CVSS Score Source: CVE-2021-28708

CVSS v3

Risk Factor: High

Base Score: 8.8

Temporal Score: 7.7

Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

Exploit Ease: No known exploits are available

Vulnerability Publication Date: 11/24/2021

Reference Information

CVE: CVE-2021-28704, CVE-2021-28705, CVE-2021-28706, CVE-2021-28707, CVE-2021-28708

IAVB: 2021-B-0068-S

Detections

Analytics