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high 7.8

CVE-2020-15567 json

An issue was discovered in Xen through 4.13.x, allowing Intel guest OS users to gain privileges or cause a denial of service because of non…

published 6y ago modified 4mo ago also EUVD-2020-7554

cvss
7.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 20%
public exploits
0
none known

Summary

An issue was discovered in Xen through 4.13.x, allowing Intel guest OS users to gain privileges or cause a denial of service because of non-atomic modification of a live EPT PTE. When mapping guest EPT (nested paging) tables, Xen would in some circumstances use a series of non-atomic bitfield writes. Depending on the compiler version and optimisation flags, Xen might expose a dangerous partially written PTE to the hardware, which an attacker might be able to race to exploit. A guest administrator or perhaps even an unprivileged guest user might be able to cause denial of service, data corruption, or privilege escalation. Only systems using Intel CPUs are vulnerable. Systems using AMD CPUs, and Arm systems, are not vulnerable. Only systems using nested paging (hap, aka nested paging, aka in this case Intel EPT) are vulnerable. Only HVM and PVH guests can exploit the vulnerability. The presence and scope of the vulnerability depends on the precise optimisations performed by the compiler used to build Xen. If the compiler generates (a) a single 64-bit write, or (b) a series of read-modify-write operations in the same order as the source code, the hypervisor is not vulnerable. For example, in one test build using GCC 8.3 with normal settings, the compiler generated multiple (unlocked) read-modify-write operations in source-code order, which did not constitute a vulnerability. We have not been able to survey compilers; consequently we cannot say which compiler(s) might produce vulnerable code (with which code-generation options). The source code clearly violates the C rules, and thus should be considered vulnerable.

Patch / fix

  • xen Debian 14, Debian 13, Debian 12 4.11.4+24-gddaaccbbab-1

debian advisories DEBIAN-CVE-2020-15567

  • xen Ubuntu 20.04 LTS 4.11.3+24-g14b62ab3e5-1ubuntu2.3

ubuntu advisories UBUNTU-CVE-2020-15567

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • xen SLES for SAP 12 SP2, SLES 12 SP2-LTSS, SLES 12 SP2-BCL +1 more 4.7.6_10-43.67.1
  • xen SLE Module for Server Applications 15 SP2, SLE Module for Basesystem 15 SP2 4.13.1_04-3.4.1
  • xen SLES for SAP 12 SP4, SLES 12 SP4-LTSS, OpenStack Cloud Crowbar 9 +1 more 4.11.4_04-2.30.1
  • xen SLE Module for Server Applications 15 SP1, SLE Module for Basesystem 15 SP1 4.12.3_04-3.22.1
  • xen SLES for SAP 15, SLE High Performance Computing 15-LTSS, SLE High Performance Computing 15-ESPOS 4.10.4_12-3.35.1
  • xen SLES for SAP 12 SP5, SLES 12 SP5, SLE Software Development Kit 12 SP5 4.12.3_04-3.18.1
  • xen SLES for SAP 12 SP3, SLES 12 SP3-LTSS, SLES 12 SP3-BCL +4 more 4.9.4_08-3.66.1
  • xen SLES 11 SP4-LTSS 4.4.4_44-61.55.1

suse advisories SUSE-SU-2020:14521-1SUSE-SU-2020:2822-1SUSE-SU-2020:1902-1SUSE-SU-2020:1891-1SUSE-SU-2020:1889-1SUSE-SU-2020:1888-1

  • xen openSUSE Tumbleweed 4.15.1_01-1.2
  • xen openSUSE Leap 15.2 4.13.1_04-lp152.2.3.1
  • xen openSUSE Leap 15.1 4.12.3_04-lp151.2.21.1

opensuse advisories openSUSE-SU-2024:11520-1openSUSE-SU-2020:0985-1openSUSE-SU-2020:0965-1

  • xen Alpine 3.10 4.12.3-r2
  • xen Alpine 3.12, Alpine 3.11 4.13.1-r2
  • xen Alpine 3.24, Alpine 3.23, Alpine 3.22 +9 more 4.13.1-r4
  • xen Alpine 3.9 4.11.4-r0

alpine advisories ALPINE-CVE-2020-15567

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-2020-15567 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-2020-15567 updated cvss 7.5

xen: non-atomic modification of live EPT PTE leads to DoS (XSA-328)

  • Red Hat Enterprise Linux 5 kernel-xen
    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

0.28% chance of exploitation in the next 30 days, higher than 20% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
NVD 3.1 7.8 CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
NVD 2.0 4.4 AV:L/AC:M/Au:N/C:P/I:P/A:P

Classification

Weakness
  • CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization

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.