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Fencer Vulns
medium 5.5

CVE-2021-26932 json

An issue was discovered in the Linux kernel 3.2 through 5.10.16, as used by Xen.

published 2021-02-17 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-13714

cvss
5.5
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 28%
public exploits
0
none known

Summary

An issue was discovered in the Linux kernel 3.2 through 5.10.16, as used by Xen. Grant mapping operations often occur in batch hypercalls, where a number of operations are done in a single hypercall, the success or failure of each one is reported to the backend driver, and the backend driver then loops over the results, performing follow-up actions based on the success or failure of each operation. Unfortunately, when running in PV mode, the Linux backend drivers mishandle this: Some errors are ignored, effectively implying their success from the success of related batch elements. In other cases, errors resulting from one batch element lead to further batch elements not being inspected, and hence successful ones to not be possible to properly unmap upon error recovery. Only systems with Linux backends running in PV mode are vulnerable. Linux backends run in HVM / PVH modes are not vulnerable. This affects arch/*/xen/p2m.c and drivers/xen/gntdev.c.

Patch / fix

  • linux Debian 14, Debian 13, Debian 12 5.10.19-1

debian advisories DEBIAN-CVE-2021-26932

  • linux Ubuntu 16.04 LTS 4.4.0-208.240
  • linux Ubuntu 18.04 LTS 4.15.0-143.147
  • linux Ubuntu 20.04 LTS 5.4.0-71.79
  • linux-aws Ubuntu 16.04 LTS 4.4.0-1126.140
  • linux-aws Ubuntu 18.04 LTS 4.15.0-1102.109
  • linux-aws Ubuntu 20.04 LTS 5.4.0-1043.45
  • linux-gcp Ubuntu 20.04 LTS 5.4.0-1041.44
  • linux-gke Ubuntu 20.04 LTS 5.4.0-1041.43

ubuntu advisories UBUNTU-CVE-2021-26932

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 SP5, SLES 12 SP5 4.12.14-122.66.2
  • kernel-source SLES for SAP 12 SP5, SLES 12 SP5 4.12.14-122.66.2
  • kernel-default SLES for SAP 12 SP5, SLES 12 SP5, SLE Workstation Extension 12 SP5 +2 more 4.12.14-122.66.2
  • kernel-obs-build SLE Software Development Kit 12 SP5 4.12.14-122.66.2
  • kernel-rt SLE Real Time 12 SP5 4.12.14-10.37.1
  • kernel-syms-rt SLE Real Time 12 SP5 4.12.14-10.37.1
  • kernel-rt_debug SLE Real Time 12 SP5 4.12.14-10.37.1
  • kernel-source-rt SLE Real Time 12 SP5 4.12.14-10.37.1

suse advisories SUSE-SU-2021:1210-1SUSE-SU-2021:1176-1SUSE-SU-2021:1175-1SUSE-SU-2021:0744-1SUSE-SU-2021:0743-1SUSE-SU-2021:0741-1

  • kernel-syms openSUSE Leap 15.2 5.3.18-lp152.66.2
  • kernel-obs-qa openSUSE Leap 15.2 5.3.18-lp152.66.2
  • kernel-source openSUSE Leap 15.2 5.3.18-lp152.66.2
  • kernel-default openSUSE Leap 15.2 5.3.18-lp152.66.2
  • kernel-preempt openSUSE Leap 15.2 5.3.18-lp152.66.2
  • kernel-kvmsmall openSUSE Leap 15.2 5.3.18-lp152.66.2
  • kernel-obs-build openSUSE Leap 15.2 5.3.18-lp152.66.2
  • kernel-default-base openSUSE Leap 15.2 5.3.18-lp152.66.2.lp152.8.23.2

opensuse advisories openSUSE-SU-2021:0393-1

  • linux Arch Linux 5.11.1.arch1-1
  • linux-hardened Arch Linux 5.10.18.hardened1-1
  • linux-zen Arch Linux 5.11.1.zen1-1
  • linux-lts Arch Linux 5.10.18-1

arch linux advisories AVG-1580AVG-1613AVG-1614AVG-1615

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-2021-26932 updated cvss 5.9

xen: Linux: grant mapping error handling issues

  • 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 28% of all scored CVEs (FIRST EPSS, 2026-11-08).

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 1.9 AV:L/AC:M/Au:N/C:N/I:N/A:P

Classification

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.