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Fencer Vulns
high 7.0

CVE-2021-3348 json

nbd_add_socket in drivers/block/nbd.c in the Linux kernel through 5.10.12 has an ndb_queue_rq use-after-free that could be triggered by loc…

published 2021-02-01 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-26679

cvss
7.0
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 18%
public exploits
0
none known

Summary

nbd_add_socket in drivers/block/nbd.c in the Linux kernel through 5.10.12 has an ndb_queue_rq use-after-free that could be triggered by local attackers (with access to the nbd device) via an I/O request at a certain point during device setup, aka CID-b98e762e3d71.

Patch / fix

  • linux Debian 14, Debian 13, Debian 12 5.10.13-1

debian advisories DEBIAN-CVE-2021-3348

  • linux Ubuntu 18.04 LTS 4.15.0-141.145
  • linux Ubuntu 20.04 LTS 5.4.0-71.79
  • linux-aws Ubuntu 18.04 LTS 4.15.0-1098.105
  • linux-aws Ubuntu 20.04 LTS 5.4.0-1043.45
  • linux-gcp Ubuntu 16.04 LTS 4.15.0-1097.110~16.04.1
  • linux-gcp Ubuntu 20.04 LTS 5.4.0-1041.44
  • linux-gke Ubuntu 20.04 LTS 5.4.0-1041.43
  • linux-hwe Ubuntu 16.04 LTS 4.15.0-142.146~16.04.1

ubuntu advisories UBUNTU-CVE-2021-3348

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 4.18.0-348.el8
  • perf RHEL 8 4.18.0-348.el8
  • bpftool RHEL 8 4.18.0-348.el8
  • kernel-core RHEL 8 4.18.0-348.el8
  • kernel-tools RHEL 8 4.18.0-348.el8
  • python3-perf RHEL 8 4.18.0-348.el8
  • kernel-modules RHEL 8 4.18.0-348.el8
  • kernel-zfcpdump RHEL 8 4.18.0-348.el8

red hat advisories RHSA-2021:4356RHSA-2021:4140

  • kernel-syms SLES for SAP 12 SP5, SLES 12 SP5 4.12.14-122.63.1
  • kernel-source SLES for SAP 12 SP5, SLES 12 SP5 4.12.14-122.63.1
  • kernel-default SLES for SAP 12 SP5, SLES 12 SP5, SLE Workstation Extension 12 SP5 +2 more 4.12.14-122.63.1
  • kernel-obs-build SLE Software Development Kit 12 SP5 4.12.14-122.63.1
  • kernel-azure SLES for SAP 12 SP5, SLES 12 SP5 4.12.14-16.47.1
  • kernel-syms-azure SLES for SAP 12 SP5, SLES 12 SP5 4.12.14-16.47.1
  • kernel-source-azure SLES for SAP 12 SP5, SLES 12 SP5 4.12.14-16.47.1
  • kernel-syms SLES for SAP 15 SP1, SLES 15 SP1-LTSS, SLES 15 SP1-BCL +6 more 4.12.14-197.83.1

suse advisories SUSE-SU-2021:0742-1SUSE-SU-2021:0739-1SUSE-SU-2021:0532-1SUSE-SU-2021:0438-1SUSE-SU-2021:0434-1SUSE-SU-2021:0433-1

  • kernel-syms openSUSE Leap 15.2 5.3.18-lp152.63.1
  • kernel-obs-qa openSUSE Leap 15.2 5.3.18-lp152.63.1
  • kernel-source openSUSE Leap 15.2 5.3.18-lp152.63.1
  • kernel-default openSUSE Leap 15.2 5.3.18-lp152.63.1
  • kernel-preempt openSUSE Leap 15.2 5.3.18-lp152.63.1
  • kernel-kvmsmall openSUSE Leap 15.2 5.3.18-lp152.63.1
  • kernel-obs-build openSUSE Leap 15.2 5.3.18-lp152.63.1
  • kernel-default-base openSUSE Leap 15.2 5.3.18-lp152.63.1.lp152.8.21.1

opensuse advisories openSUSE-SU-2021:0241-1

  • linux Arch Linux 5.10.13.arch1-1
  • linux-hardened Arch Linux 5.10.13.hardened1-1
  • linux-zen Arch Linux 5.10.13.zen1-1
  • linux-lts Arch Linux 5.4.95-1

arch linux advisories AVG-1512AVG-1513AVG-1514AVG-1515

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-2021-3348 updated cvss 7.0

kernel: Use-after-free in ndb_queue_rq() in drivers/block/nbd.c

  • Red Hat Enterprise Linux 5 kernel
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat CodeReady Linux Builder (v. 8) kernel-debuginfo-common-x86_64 4.18.0-348.el8, kernel-debuginfo-common-aarch64 4.18.0-348.el8, kernel-debuginfo-common-ppc64le 4.18.0-348.el8 Red Hat Enterprise Linux BaseOS (v. 8) perf 4.18.0-348.el8, kernel 4.18.0-348.el8, bpftool 4.18.0-348.el8, kernel-core 4.18.0-348.el8, kernel-tools 4.18.0-348.el8, python3-perf 4.18.0-348.el8, +15 more
    fixed: vendor fix RHSA-2021:4356
  • Red Hat Enterprise Linux Real Time (v. 8) kernel-rt 4.18.0-348.rt7.130.el8, kernel-rt-core 4.18.0-348.rt7.130.el8, kernel-rt-modules 4.18.0-348.rt7.130.el8, kernel-rt-debug-core 4.18.0-348.rt7.130.el8, kernel-rt-debug-modules 4.18.0-348.rt7.130.el8, kernel-rt-modules-extra 4.18.0-348.rt7.130.el8, +2 more Red Hat Enterprise Linux Real Time for NFV (v. 8) kernel-rt 4.18.0-348.rt7.130.el8, kernel-rt-kvm 4.18.0-348.rt7.130.el8, kernel-rt-core 4.18.0-348.rt7.130.el8, kernel-rt-modules 4.18.0-348.rt7.130.el8, kernel-rt-debug-kvm 4.18.0-348.rt7.130.el8, kernel-rt-debug-core 4.18.0-348.rt7.130.el8, +4 more
    fixed: vendor fix RHSA-2021:4140
  • 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 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

Exploit prediction

0.26% chance of exploitation in the next 30 days, higher than 18% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 7.0 CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 4.4 AV:L/AC:M/Au:N/C:P/I:P/A:P

Classification

Weakness
  • CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization
  • CWE-416 Use After Free
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.