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Fencer Vulns
low 2.3

CVE-2021-3923 json

A flaw was found in the Linux kernel's implementation of RDMA over infiniband.

published 2023-03-27 3 y ago modified 2026-06-17 4 mo ago also EUVD-2021-27140

cvss
2.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 9%
public exploits
0
none known

Summary

A flaw was found in the Linux kernel's implementation of RDMA over infiniband. An attacker with a privileged local account can leak kernel stack information when issuing commands to the /dev/infiniband/rdma_cm device node. While this access is unlikely to leak sensitive user information, it can be further used to defeat existing kernel protection mechanisms.

Patch / fix

  • linux linux_kernel 5.15.14
  • linux Debian 14, Debian 13, Debian 12 5.15.15-1

debian advisories DEBIAN-CVE-2021-3923

  • linux Ubuntu 18.04 LTS 4.15.0-173.182
  • linux Ubuntu 20.04 LTS 5.4.0-105.119
  • linux-aws Ubuntu 18.04 LTS 4.15.0-1124.133
  • linux-aws Ubuntu 20.04 LTS 5.4.0-1069.73
  • linux-gcp Ubuntu 20.04 LTS 5.4.0-1068.72
  • linux-gke Ubuntu 20.04 LTS 5.4.0-1066.69
  • linux-ibm Ubuntu 20.04 LTS 5.4.0-1018.20
  • linux-kvm Ubuntu 18.04 LTS 4.15.0-1110.113

ubuntu advisories UBUNTU-CVE-2021-3923

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 4.18.0-372.9.1.el8
  • perf RHEL 8 4.18.0-372.9.1.el8
  • bpftool RHEL 8 4.18.0-372.9.1.el8
  • kernel-core RHEL 8 4.18.0-372.9.1.el8
  • kernel-tools RHEL 8 4.18.0-372.9.1.el8
  • python3-perf RHEL 8 4.18.0-372.9.1.el8
  • kernel-modules RHEL 8 4.18.0-372.9.1.el8
  • kernel-zfcpdump RHEL 8 4.18.0-372.9.1.el8

red hat advisories RHSA-2022:1988RHSA-2022:1975

  • kernel-syms SLES for SAP 15 SP2, SLES 15 SP2-LTSS, SLE High Performance Computing 15 SP2-LTSS +1 more 5.3.18-150200.24.148.1
  • kernel-source SLES for SAP 15 SP2, SLES 15 SP2-LTSS, SLE High Performance Computing 15 SP2-LTSS +1 more 5.3.18-150200.24.148.1
  • kernel-default SLES for SAP 15 SP2, SLES 15 SP2-LTSS, SLE Live Patching 15 SP2 +3 more 5.3.18-150200.24.148.1
  • kernel-preempt SLES for SAP 15 SP2, SLES 15 SP2-LTSS, SLE High Performance Computing 15 SP2-LTSS +1 more 5.3.18-150200.24.148.1
  • kernel-obs-build SLES for SAP 15 SP2, SLES 15 SP2-LTSS, SLE High Performance Computing 15 SP2-LTSS +1 more 5.3.18-150200.24.148.1
  • kernel-default-base SLES for SAP 15 SP2, SLES 15 SP2-LTSS, SLE High Performance Computing 15 SP2-LTSS +1 more 5.3.18-150200.24.148.1.150200.9.71.1
  • dtb-aarch64 openSUSE Leap 15.4 5.3.18-150300.59.118.1
  • kernel-64kb SLES 15 SP3-LTSS, SLE High Performance Computing 15 SP3-LTSS, SLE High Performance Computing 15 SP3-ESPOS +1 more 5.3.18-150300.59.118.1

suse advisories SUSE-SU-2023:1800-1SUSE-SU-2023:1811-1SUSE-SU-2023:1892-1SUSE-SU-2023:1848-1SUSE-SU-2023:2232-1SUSE-SU-2023:1894-1

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-2021-3923 updated cvss 3.3

kernel: stack information leak in infiniband RDMA

  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Enterprise Linux BaseOS (v. 8) perf 4.18.0-372.9.1.el8, kernel 4.18.0-372.9.1.el8, bpftool 4.18.0-372.9.1.el8, kernel-core 4.18.0-372.9.1.el8, kernel-tools 4.18.0-372.9.1.el8, python3-perf 4.18.0-372.9.1.el8, +15 more Red Hat Enterprise Linux CRB (v. 8) kernel-debuginfo-common-x86_64 4.18.0-372.9.1.el8, kernel-debuginfo-common-aarch64 4.18.0-372.9.1.el8, kernel-debuginfo-common-ppc64le 4.18.0-372.9.1.el8
    fixed: vendor fix RHSA-2022:1988
  • Red Hat Enterprise Linux NFV (v. 8) kernel-rt 4.18.0-372.9.1.rt7.166.el8, kernel-rt-kvm 4.18.0-372.9.1.rt7.166.el8, kernel-rt-core 4.18.0-372.9.1.rt7.166.el8, kernel-rt-modules 4.18.0-372.9.1.rt7.166.el8, kernel-rt-debug-kvm 4.18.0-372.9.1.rt7.166.el8, kernel-rt-debug-core 4.18.0-372.9.1.rt7.166.el8, +4 more Red Hat Enterprise Linux RT (v. 8) kernel-rt 4.18.0-372.9.1.rt7.166.el8, kernel-rt-core 4.18.0-372.9.1.rt7.166.el8, kernel-rt-modules 4.18.0-372.9.1.rt7.166.el8, kernel-rt-debug-core 4.18.0-372.9.1.rt7.166.el8, kernel-rt-debug-modules 4.18.0-372.9.1.rt7.166.el8, kernel-rt-modules-extra 4.18.0-372.9.1.rt7.166.el8, +2 more
    fixed: vendor fix RHSA-2022:1975
  • Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +82 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

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
20 mo ago

Exploit prediction

0.20% chance of exploitation in the next 30 days, higher than 9% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CISA ADP 3.1 2.3 CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:N/A:N
NVD 3.1 2.3 CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:N/A:N
CNA 3.1 2.3 CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:N/A:N

Affected products

  • n/a kernel

Classification

Weakness
  • CWE-200 Exposure of Sensitive Information to an Unauthorized Actor
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.