CVE-2021-45868: linux linux_kernel Use After Free

Modified

AliasesUBUNTU-CVE-2021-45868DEBIAN-CVE-2021-45868

Published 18-03-2022Last modified 04-08-2024

Vulnerability summary

CVE-2021-45868 is a medium (CVSS 5.5) Use After Free vulnerability in linux linux_kernel. EPSS estimates a 1.34% chance of exploitation in the next 30 days, higher than 71.3% of scored vulnerabilities. 3 public exploits are recorded.

Priority

Routine

Not severe (CVSS 5.5, local access); no exploitation reported by the 5 checked sources

Source freshness unavailable

How is this decided?

CVSS score

5.5/10

010

Medium · v3.1 (NVD)

EPSS score

1.34%

0%100%

Low · 0.00 pp in 30 days

KEVNot listedNot listed by any tracked catalog.

RansomwareNot flaggedNo ransomware use recorded.

Public exploits3reference

Advisory lineage

Upstream 0 · Downstream 17 · Related 17

SUSE-SU-2022:1163-1 SUSE-SU-2022:1183-1 SUSE-SU-2022:1196-1 SUSE-SU-2022:1197-1 SUSE-SU-2022:1255-1 SUSE-SU-2022:1256-1+11 more

Timeline

18-03-2022
PublishedVulnerability first disclosed.
04-08-2024
Last modifiedVulnerability information updated.

Description

In the Linux kernel before 5.15.3, fs/quota/quota_tree.c does not validate the block number in the quota tree (on disk). This can, for example, lead to a kernel/locking/rwsem.c use-after-free if there is a corrupted quota file.

CVSS metrics

5 scores · 3 sources · 3 versions

v4.07.1v3.15.5v2.04.3

EPSS trend

Probability

1.34%

Chance of exploitation in the next 30 days

Percentile

71%

Versus all other CVEs

30-day change

No change 0.00 pp

From 1.34% on 04-10-2026

04-10-202603-11-2026

Known exploited

Compare KEV catalogs

CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

3 found

referenceUnverified
Exploit Reference (bugzilla.kernel.org)
Maturity: unknown
referenceUnverified
Exploit Reference (openwall.com)
Maturity: unknown
referenceUnverified
Exploit Reference (openwall.com)
Maturity: unknown

Weaknesses

CWE · root cause

CWE-416Use After FreeThe product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.

Affected systems

Version check

Known conditions: local access, no authentication, user interaction (CVSS vector). Other conditions: not stated in public data.

Ubuntu68 products

linuxAll versions (No fix recorded) | < 4.4.0-239.273 | < 4.15.0-167.175 | < 5.4.0-97.110
linux-aws< 4.4.0-1117.123 | < 4.4.0-1155.170 | < 4.15.0-1119.127 | < 5.4.0-1064.67
linux-aws-5.0All versions (No fix recorded)
linux-aws-5.11All versions (No fix recorded)
linux-aws-5.13< 5.13.0-1012.13~20.04.1

linux-aws-5.3All versions (No fix recorded)
linux-aws-5.4< 5.4.0-1064.67~18.04.1
linux-aws-5.8All versions (No fix recorded)
linux-aws-fips< 4.15.0-2060.62 | All versions (No fix recorded) | < 5.4.0-1069.73+fips2
linux-aws-hwe< 4.15.0-1119.126~16.04.2
linux-azure< 4.15.0-1130.143~14.04.1 | < 4.15.0-1130.143~16.04.1 | All versions (No fix recorded) | < 5.4.0-1068.71
linux-azure-4.15< 4.15.0-1131.144
linux-azure-5.11All versions (No fix recorded)
linux-azure-5.13< 5.13.0-1013.15~20.04.1
linux-azure-5.3All versions (No fix recorded)
linux-azure-5.4< 5.4.0-1068.71~18.04.1
linux-azure-5.8All versions (No fix recorded)
linux-azure-edgeAll versions (No fix recorded)
linux-azure-fips< 4.15.0-2042.46 | All versions (No fix recorded) | < 5.4.0-1073.76+fips1
linux-bluefield< 5.4.0-1026.29
linux-dell300x< 4.15.0-1034.39
linux-fips< 4.4.0-1088.95 | All versions (No fix recorded) | < 4.15.0-1076.85 | < 5.4.0-1041.47
linux-gcp< 4.15.0-1115.129~16.04.1 | All versions (No fix recorded) | < 5.4.0-1063.67
linux-gcp-4.15< 4.15.0-1115.129
linux-gcp-5.11All versions (No fix recorded)
linux-gcp-5.13< 5.13.0-1013.16~20.04.1
linux-gcp-5.3All versions (No fix recorded)
linux-gcp-5.4< 5.4.0-1063.67~18.04.1
linux-gcp-5.8All versions (No fix recorded)
linux-gcp-fips< 4.15.0-2025.27 | All versions (No fix recorded) | < 5.4.0-1067.71~20.04.1
linux-gke< 5.4.0-1061.64
linux-gke-4.15All versions (No fix recorded)
linux-gke-5.4< 5.4.0-1061.64~18.04.1
linux-gkeop< 5.4.0-1032.33
linux-gkeop-5.4< 5.4.0-1032.33~18.04.1
linux-hwe< 4.15.0-167.175~16.04.1 | All versions (No fix recorded)
linux-hwe-5.11All versions (No fix recorded)
linux-hwe-5.13< 5.13.0-28.31~20.04.1
linux-hwe-5.4< 5.4.0-97.110~18.04.1
linux-hwe-5.8All versions (No fix recorded)
linux-hwe-edgeAll versions (No fix recorded)
linux-ibm< 5.4.0-1013.14
linux-ibm-5.4< 5.4.0-1014.15~18.04.1
linux-intel-5.13All versions (No fix recorded)
linux-intel-iot-realtimeAll versions (No fix recorded)
linux-kvm< 4.4.0-1118.128 | < 4.15.0-1106.108 | < 5.4.0-1054.56
linux-lts-xenial< 4.4.0-239.273~14.04.1
linux-oemAll versions (No fix recorded)
linux-oem-5.10All versions (No fix recorded)
linux-oem-5.13All versions (No fix recorded)
linux-oem-5.14< 5.14.0-1013.13
linux-oem-5.6All versions (No fix recorded)
linux-oracle< 4.15.0-1086.94~16.04.1 | < 4.15.0-1086.94 | < 5.4.0-1062.66
linux-oracle-5.0All versions (No fix recorded)
linux-oracle-5.11All versions (No fix recorded)
linux-oracle-5.13< 5.13.0-1016.20~20.04.1
linux-oracle-5.3All versions (No fix recorded)
linux-oracle-5.4< 5.4.0-1062.66~18.04.1
linux-oracle-5.8All versions (No fix recorded)
linux-raspi< 5.4.0-1052.58
linux-raspi-5.4< 5.4.0-1052.58~18.04.1
linux-raspi-realtimeAll versions (No fix recorded)
linux-raspi2< 4.15.0-1102.109 | All versions (No fix recorded)
linux-realtimeAll versions (No fix recorded)
linux-riscvAll versions (No fix recorded)
linux-riscv-5.11All versions (No fix recorded)
linux-riscv-5.8All versions (No fix recorded)
linux-snapdragon< 4.15.0-1119.128