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Fencer Vulns
high 7.8

CVE-2020-25595 json

An issue was discovered in Xen through 4.14.x.

published 2020-09-23 6 y ago modified 2026-06-17 4 mo ago also EUVD-2020-18274

cvss
7.8
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 31%
public exploits
0
none known

Summary

An issue was discovered in Xen through 4.14.x. The PCI passthrough code improperly uses register data. Code paths in Xen's MSI handling have been identified that act on unsanitized values read back from device hardware registers. While devices strictly compliant with PCI specifications shouldn't be able to affect these registers, experience shows that it's very common for devices to have out-of-spec "backdoor" operations that can affect the result of these reads. A not fully trusted guest may be able to crash Xen, leading to a Denial of Service (DoS) for the entire system. Privilege escalation and information leaks cannot be excluded. All versions of Xen supporting PCI passthrough are affected. Only x86 systems are vulnerable. Arm systems are not vulnerable. Only guests with passed through PCI devices may be able to leverage the vulnerability. Only systems passing through devices with out-of-spec ("backdoor") functionality can cause issues. Experience shows that such out-of-spec functionality is common; unless you have reason to believe that your device does not have such functionality, it's better to assume that it does.

Patch / fix

  • xen Debian 14, Debian 13, Debian 12 4.14.0+80-gd101b417b7-1

debian advisories DEBIAN-CVE-2020-25595

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

ubuntu advisories UBUNTU-CVE-2020-25595

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_08-3.10.1
  • xen SLE Module for Server Applications 15 SP1, SLE Module for Basesystem 15 SP1 4.12.3_08-3.28.1
  • xen SLES for SAP 15, SLE High Performance Computing 15-LTSS, SLE High Performance Computing 15-ESPOS 4.10.4_16-3.41.1
  • xen SLES for SAP 12 SP5, SLES 12 SP5, SLE Software Development Kit 12 SP5 4.12.3_08-3.24.1
  • xen SLES for SAP 12 SP3, SLES 12 SP3-LTSS, SLES 12 SP3-BCL +4 more 4.9.4_12-3.74.1
  • xen SLES for SAP 12 SP4, SLES 12 SP4-LTSS, OpenStack Cloud Crowbar 9 +1 more 4.11.4_08-2.36.1
  • xen SLES 11 SP4-LTSS 4.4.4_44-61.55.1

suse advisories SUSE-SU-2020:14521-1SUSE-SU-2020:2822-1SUSE-SU-2020:2791-1SUSE-SU-2020:2790-1SUSE-SU-2020:2789-1SUSE-SU-2020:2788-1

  • xen openSUSE Tumbleweed 4.15.1_01-1.2
  • xen openSUSE Leap 15.2 4.13.1_08-lp152.2.9.1

opensuse advisories openSUSE-SU-2024:11520-1openSUSE-SU-2020:1608-1

  • xen Alpine 3.10 4.12.3-r4
  • xen Alpine 3.12, Alpine 3.11 4.13.1-r4
  • xen Alpine 3.24, Alpine 3.23, Alpine 3.22 +9 more 4.14.0-r1
  • xen Alpine 3.9 4.11.4-r2

alpine advisories ALPINE-CVE-2020-25595

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

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-2020-25595 updated cvss 7.0

xen: PCI passthrough code reading back hardware registers (XSA-337)

  • Red Hat Enterprise Linux 5 kernel-xen
    affected: workaround, no fix planned “Avoid pass-through of physical devices to untrusted guests.”

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

0.37% chance of exploitation in the next 30 days, higher than 31% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 6.1 AV:L/AC:L/Au:N/C:P/I:P/A:C

Classification

Weakness
  • CWE-269 Improper Privilege Management

References

Sources

Fencer Vulns 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.