8.8

CVE-2021-3492: Ubuntu linux kernel shiftfs file system double free vulnerability

Modified
AliasesLSN-0077-1UBUNTU-CVE-2021-3492
Published 17-04-2021Last modified 17-09-2024

Vulnerability summary

CVE-2021-3492 is a high (CVSS 8.8) vulnerability in canonical ubuntu_linux. EPSS estimates a 1.54% chance of exploitation in the next 30 days, higher than 74.8% of scored vulnerabilities.

Priority
Routine

Not severe (CVSS 8.8, local access); no exploitation reported by the 5 checked sources

Source freshness unavailable

How is this decided?
CVSS score
8.8/10
010
High · v3.1 (CVE.org)
EPSS score
1.54%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 2 · Related 2
USN-4915-1USN-4917-1

Timeline

  1. 17-04-2021
    PublishedVulnerability first disclosed.
  2. 17-09-2024
    Last modifiedVulnerability information updated.

Description

Shiftfs, an out-of-tree stacking file system included in Ubuntu Linux kernels, did not properly handle faults occurring during copy_from_user() correctly. These could lead to either a double-free situation or memory not being freed at all. An attacker could use this to cause a denial of service (kernel memory exhaustion) or gain privileges via executing arbitrary code. AKA ZDI-CAN-13562.

CVSS metrics

4 scores · 3 sources · 2 versions

EPSS trend

Probability

1.54%

Chance of exploitation in the next 30 days

Percentile

75%

Versus all other CVEs

30-day change

No change 0.00 pp

From 1.54% 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

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Version check

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

Ubuntu41 products
  • linux< 5.4.0-72.80
  • linux-aws< 5.4.0-1045.47
  • linux-aws-5.0All versions (No fix recorded)
  • linux-aws-5.3All versions (No fix recorded)
  • linux-aws-5.4< 5.4.0-1045.47~18.04.1
Canonical1 product

2 vendors · 42 products

References

10 links