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Fencer Vulns
medium 4.4

CVE-2020-27835 json

A use after free in the Linux kernel infiniband hfi1 driver in versions prior to 5.10-rc6 was found in the way user calls Ioctl after open…

published 2021-01-07 5 y ago modified 2026-06-17 4 mo ago also EUVD-2020-20334

cvss
4.4
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 24%
public exploits
0
none known

Summary

A use after free in the Linux kernel infiniband hfi1 driver in versions prior to 5.10-rc6 was found in the way user calls Ioctl after open dev file and fork. A local user could use this flaw to crash the system.

Patch / fix

  • linux Debian 14, Debian 13, Debian 12 5.9.15-1

debian advisories DEBIAN-CVE-2020-27835

  • linux-hwe-5.8 Ubuntu 20.04 LTS 5.8.0-44.50~20.04.1
  • linux-riscv-5.8 Ubuntu 20.04 LTS 5.8.0-17.19~20.04.1

ubuntu advisories UBUNTU-CVE-2020-27835

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 RHEL 8 4.18.0-305.el8
  • perf RHEL 8 4.18.0-305.el8
  • bpftool RHEL 8 4.18.0-305.el8
  • kernel-core RHEL 8 4.18.0-305.el8
  • kernel-tools RHEL 8 4.18.0-305.el8
  • python3-perf RHEL 8 4.18.0-305.el8
  • kernel-modules RHEL 8 4.18.0-305.el8
  • kernel-zfcpdump RHEL 8 4.18.0-305.el8

red hat advisories RHSA-2021:1578RHSA-2021:1739

  • kernel-64kb SLES 15 SP3-LTSS, SLE High Performance Computing 15 SP3-LTSS, Enterprise Storage 7.1 5.3.18-150300.59.201.1
  • kernel-syms SLES for SAP 15 SP3, SLES 15 SP3-LTSS, SLE High Performance Computing 15 SP3-LTSS +1 more 5.3.18-150300.59.201.1
  • kernel-source SLES for SAP 15 SP3, SLES 15 SP3-LTSS, SLE High Performance Computing 15 SP3-LTSS +1 more 5.3.18-150300.59.201.1
  • kernel-default SLES for SAP 15 SP3, SLES 15 SP3-LTSS, SLE Micro 5.2 +5 more 5.3.18-150300.59.201.1
  • kernel-preempt SLES for SAP 15 SP3, SLES 15 SP3-LTSS, SLE High Performance Computing 15 SP3-LTSS +1 more 5.3.18-150300.59.201.1
  • kernel-obs-build SLES for SAP 15 SP3, SLES 15 SP3-LTSS, SLE High Performance Computing 15 SP3-LTSS +1 more 5.3.18-150300.59.201.1
  • kernel-default-base SLES for SAP 15 SP3, SLES 15 SP3-LTSS, SLE Micro 5.2 +3 more 5.3.18-150300.59.201.1.150300.18.120.1
  • kernel-rt SLE Micro 5.2, SLE Micro 5.1 5.3.18-150300.205.1

suse advisories SUSE-SU-2025:1263-1SUSE-SU-2025:1194-1SUSE-SU-2022:1687-1SUSE-SU-2022:1676-1SUSE-SU-2022:1669-1SUSE-SU-2021:0532-1

  • kernel-syms openSUSE Leap 15.2 5.3.18-lp152.60.1
  • kernel-obs-qa openSUSE Leap 15.2 5.3.18-lp152.60.1
  • kernel-source openSUSE Leap 15.2 5.3.18-lp152.60.1
  • kernel-default openSUSE Leap 15.2 5.3.18-lp152.60.1
  • kernel-preempt openSUSE Leap 15.2 5.3.18-lp152.60.1
  • kernel-kvmsmall openSUSE Leap 15.2 5.3.18-lp152.60.1
  • kernel-obs-build openSUSE Leap 15.2 5.3.18-lp152.60.1

opensuse advisories openSUSE-SU-2021:0060-1

  • linux Arch Linux 5.9.12.arch1-1

arch linux advisories AVG-1344

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-2020-27835 updated cvss 6.4

kernel: child process is able to access parent mm through hfi dev file handle

  • Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, kernel-alt, python-perf, +9 more
    affected: workaround, no fix planned “Will not fix”
  • Red Hat CodeReady Linux Builder (v. 8) kernel-debuginfo-common-x86_64 4.18.0-305.el8, kernel-debuginfo-common-aarch64 4.18.0-305.el8, kernel-debuginfo-common-ppc64le 4.18.0-305.el8 Red Hat Enterprise Linux BaseOS (v. 8) perf 4.18.0-305.el8, kernel 4.18.0-305.el8, bpftool 4.18.0-305.el8, kernel-core 4.18.0-305.el8, kernel-tools 4.18.0-305.el8, python3-perf 4.18.0-305.el8, +15 more
    fixed: vendor fix RHSA-2021:1578
  • Red Hat Enterprise Linux Real Time (v. 8) kernel-rt 4.18.0-305.rt7.72.el8, kernel-rt-core 4.18.0-305.rt7.72.el8, kernel-rt-modules 4.18.0-305.rt7.72.el8, kernel-rt-debug-core 4.18.0-305.rt7.72.el8, kernel-rt-debug-modules 4.18.0-305.rt7.72.el8, kernel-rt-modules-extra 4.18.0-305.rt7.72.el8, +2 more Red Hat Enterprise Linux Real Time for NFV (v. 8) kernel-rt 4.18.0-305.rt7.72.el8, kernel-rt-kvm 4.18.0-305.rt7.72.el8, kernel-rt-core 4.18.0-305.rt7.72.el8, kernel-rt-modules 4.18.0-305.rt7.72.el8, kernel-rt-debug-kvm 4.18.0-305.rt7.72.el8, kernel-rt-debug-core 4.18.0-305.rt7.72.el8, +4 more
    fixed: vendor fix RHSA-2021:1739
  • Red Hat Enterprise Linux 5 kernel Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more
    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

0.31% chance of exploitation in the next 30 days, higher than 24% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 4.4 CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 4.9 AV:L/AC:L/Au:N/C:N/I:N/A:C

Affected products

  • n/a kernel

Classification

Weakness

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.