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Fencer Vulns
high 7.8

CVE-2021-47355 json

atm: nicstar: Fix possible use-after-free in nicstar_cleanup()

published 2024-05-21 2 y ago modified 2026-06-17 4 mo ago also EUVD-2021-34360

cvss
7.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 16%
public exploits
0
none known

Summary

In the Linux kernel, the following vulnerability has been resolved:

atm: nicstar: Fix possible use-after-free in nicstar_cleanup()

This module's remove path calls del_timer(). However, that function does not wait until the timer handler finishes. This means that the timer handler may still be running after the driver's remove function has finished, which would result in a use-after-free.

Fix by calling del_timer_sync(), which makes sure the timer handler has finished, and unable to re-schedule itself.

Patch / fix

  • Linux Linux 4.4.276, 4.9.276, 4.14.240, 4.19.198, 5.4.133, 5.10.51, 5.12.18, 5.13.3, 5.14
  • linux Debian 14, Debian 13, Debian 12 5.14.6-1

debian advisories DEBIAN-CVE-2021-47355

  • linux Ubuntu 18.04 LTS 4.15.0-156.163
  • linux Ubuntu 20.04 LTS 5.4.0-84.94
  • linux-aws Ubuntu 18.04 LTS 4.15.0-1111.118
  • linux-aws Ubuntu 20.04 LTS 5.4.0-1056.59
  • linux-gcp Ubuntu 20.04 LTS 5.4.0-1052.56
  • linux-kvm Ubuntu 18.04 LTS 4.15.0-1099.101
  • linux-kvm Ubuntu 20.04 LTS 5.4.0-1046.48
  • linux-azure Ubuntu 20.04 LTS 5.4.0-1058.60

ubuntu advisories UBUNTU-CVE-2021-47355

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 4.12.14-122.219.1
  • kernel-source SLES for SAP 12 SP5, SLES 12 SP5 4.12.14-122.219.1
  • kernel-default SLES for SAP 12 SP5, SLES 12 SP5, SLE Workstation Extension 12 SP5 +2 more 4.12.14-122.219.1
  • kernel-obs-build SLE Software Development Kit 12 SP5 4.12.14-122.219.1
  • kernel-rt SLE Real Time 12 SP5 4.12.14-10.188.1
  • kernel-syms-rt SLE Real Time 12 SP5 4.12.14-10.188.1
  • kernel-rt_debug SLE Real Time 12 SP5 4.12.14-10.188.1
  • kernel-source-rt SLE Real Time 12 SP5 4.12.14-10.188.1

suse advisories SUSE-SU-2024:2184-1SUSE-SU-2024:1983-1SUSE-SU-2024:1979-1

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-2021-47355 updated cvss 6.7

kernel: atm: nicstar: Fix possible use-after-free in nicstar_cleanup()

  • 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, python-perf, kernel-kdump, +8 more Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 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
2 y ago

Exploit prediction

0.25% chance of exploitation in the next 30 days, higher than 16% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

  • Linux Linux

Classification

Weakness
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.