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Fencer Vulns
high 7.5

CVE-2021-47295 json

net: sched: fix memory leak in tcindex_partial_destroy_work

published 2024-05-21 2 y ago modified 2026-06-17 4 mo ago also EUVD-2021-34300

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.5%
EPSS 1.5% chance of exploitation in 30 days, percentile 74%
public exploits
0
none known

Summary

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

net: sched: fix memory leak in tcindex_partial_destroy_work

Syzbot reported memory leak in tcindex_set_parms(). The problem was in non-freed perfect hash in tcindex_partial_destroy_work().

In tcindex_set_parms() new tcindex_data is allocated and some fields from old one are copied to new one, but not the perfect hash. Since tcindex_partial_destroy_work() is the destroy function for old tcindex_data, we need to free perfect hash to avoid memory leak.

Patch / fix

  • Linux Linux 4.14.308, 4.19.276, 5.4.136, 5.4.235, 5.10.54, 5.10.173, 5.13.6, 5.14, 5.15.100, 6.1.18, 6.2.5
  • linux linux_kernel 8d7924ce85ba, 8e9662fde6d6, cac71d27745f, f5051bcece50
  • linux Debian 14, Debian 13, Debian 12 5.14.6-1

debian advisories DEBIAN-CVE-2021-47295

  • linux Ubuntu 20.04 LTS 5.4.0-88.99
  • linux-aws Ubuntu 20.04 LTS 5.4.0-1057.60
  • linux-gcp Ubuntu 20.04 LTS 5.4.0-1053.57
  • linux-ibm Ubuntu 20.04 LTS 5.4.0-1005.6
  • linux-kvm Ubuntu 20.04 LTS 5.4.0-1047.49
  • linux-azure Ubuntu 20.04 LTS 5.4.0-1059.62
  • linux-gkeop Ubuntu 20.04 LTS 5.4.0-1024.25
  • linux-raspi Ubuntu 20.04 LTS 5.4.0-1044.48

ubuntu advisories UBUNTU-CVE-2021-47295

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 4.12.14-122.225.1
  • kernel-source SLES for SAP 12 SP5, SLES 12 SP5 4.12.14-122.225.1
  • kernel-default SLES for SAP 12 SP5, SLES 12 SP5, SLE Workstation Extension 12 SP5 +2 more 4.12.14-122.225.1
  • kernel-obs-build SLE Software Development Kit 12 SP5 4.12.14-122.225.1
  • kernel-azure SLES for SAP 12 SP5, SLES 12 SP5 4.12.14-16.194.1
  • kernel-syms-azure SLES for SAP 12 SP5, SLES 12 SP5 4.12.14-16.194.1
  • kernel-source-azure SLES for SAP 12 SP5, SLES 12 SP5 4.12.14-16.194.1
  • kernel-rt SLE Real Time 12 SP5 4.12.14-10.197.1

suse advisories SUSE-SU-2024:2940-1SUSE-SU-2024:2901-1SUSE-SU-2024:2892-1

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-2021-47295 updated cvss 5.5

kernel: net: sched: fix memory leak in tcindex_partial_destroy_work

  • 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
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more
    affected: no fix available
  • 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
yes
Technical impact
partial
Assessed
2 y ago

Exploit prediction

1.50% chance of exploitation in the next 30 days, higher than 74% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CISA ADP 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

  • Linux Linux
  • linux linux_kernel

Classification

Weakness
  • CWE-400 Uncontrolled Resource Consumption
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.