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Fencer Vulns
medium 4.7

CVE-2020-27675 json

An issue was discovered in the Linux kernel through 5.9.1, as used with Xen through 4.14.x.

published 2020-10-22 6 y ago modified 2026-06-17 4 mo ago also EUVD-2020-20179

cvss
4.7
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 19%
public exploits
0
none known

Summary

An issue was discovered in the Linux kernel through 5.9.1, as used with Xen through 4.14.x. drivers/xen/events/events_base.c allows event-channel removal during the event-handling loop (a race condition). This can cause a use-after-free or NULL pointer dereference, as demonstrated by a dom0 crash via events for an in-reconfiguration paravirtualized device, aka CID-073d0552ead5.

Patch / fix

  • linux Debian 14, Debian 13, Debian 12 5.9.6-1

debian advisories DEBIAN-CVE-2020-27675

  • linux Ubuntu 16.04 LTS 4.4.0-198.230
  • linux Ubuntu 18.04 LTS 4.15.0-129.132
  • linux Ubuntu 20.04 LTS 5.4.0-59.65
  • linux-aws Ubuntu 16.04 LTS 4.4.0-1119.133
  • linux-aws Ubuntu 18.04 LTS 4.15.0-1091.96
  • linux-aws Ubuntu 20.04 LTS 5.4.0-1034.35
  • linux-gcp Ubuntu 16.04 LTS 4.15.0-1091.104~16.04.1
  • linux-gcp Ubuntu 20.04 LTS 5.4.0-1033.35

ubuntu advisories UBUNTU-CVE-2020-27675

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

  • kernel-syms SLES for SAP 12 SP4, SLES 12 SP4-LTSS, OpenStack Cloud Crowbar 9 +1 more 4.12.14-95.65.1
  • kernel-source SLES for SAP 12 SP4, SLES 12 SP4-LTSS, OpenStack Cloud Crowbar 9 +1 more 4.12.14-95.65.1
  • kernel-default SLES for SAP 12 SP4, SLES 12 SP4-LTSS, SLE Live Patching 12 SP4 +3 more 4.12.14-95.65.1
  • kernel-syms SLES for SAP 15, SLES 15-LTSS, SLE High Performance Computing 15-LTSS +1 more 4.12.14-150.63.1
  • kernel-source SLES for SAP 15, SLES 15-LTSS, SLE High Performance Computing 15-LTSS +1 more 4.12.14-150.63.1
  • kernel-default SLES for SAP 15, SLES 15-LTSS, SLE Live Patching 15 +3 more 4.12.14-150.63.1
  • kernel-vanilla SLES for SAP 15, SLES 15-LTSS, SLE High Performance Computing 15-LTSS +1 more 4.12.14-150.63.1
  • kernel-obs-build SLES for SAP 15, SLES 15-LTSS, SLE High Performance Computing 15-LTSS +1 more 4.12.14-150.63.1

suse advisories SUSE-SU-2020:3544-1SUSE-SU-2020:3532-1SUSE-SU-2020:3491-1SUSE-SU-2020:3281-1SUSE-SU-2020:3272-1

  • linux Arch Linux 5.9.2.arch1-1

arch linux advisories AVG-1472

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-2020-27675 updated cvss 0.0

kernel: xen: race condition in event-channel removal during the event-handling loop (XSA-331)

  • Red Hat Enterprise Linux 5 kernel
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, kernel-alt, python-perf, +9 more Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise MRG 2 kernel-rt, mrg-rt-release, kernel-rt-trace, kernel-rt-vanilla, kernel-rt-firmware
    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

0.27% chance of exploitation in the next 30 days, higher than 19% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 4.7 CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 4.7 AV:L/AC:M/Au:N/C:N/I:N/A:C

Classification

Weakness
  • CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization
  • CWE-416 Use After Free
  • CWE-476 NULL Pointer Dereference
Technology feeds

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.