PT-2021-4252 · Linux+3 · Linux Kernel+4

Vdehors + 1 · Published 2021-04-09 · Updated 2025-09-29 · CVE-2021-3492

Positive Technologies (AI Summary)

CVSS v3.1

8.8

High

Base vector

AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Name of the Vulnerable Software and Affected Versions Shiftfs versions prior to the fixed version

Description The issue is related to the copy from user() function in the shiftfs file system of the Linux kernel, which is associated with a double-free memory error. This can allow an attacker to access confidential data, compromise data integrity, and cause a denial of service. The vulnerability can also be exploited to gain privileges via executing arbitrary code. An attacker could use this to cause kernel memory exhaustion.

Recommendations At the moment, there is no information about a newer version that contains a fix for this vulnerability.

Exploit

DoS

Double Free

Memory Leak

Weakness Enumeration

CWE-415

CWE-401

Related Identifiers

ALSA-2025_16880

BDU:2021-04860

CVE-2021-3492

LSN-0077-1

USN-4915-1

USN-4917-1

ZDI-21-422

Affected Products

Astra Linux

Linuxmint

Linux Kernel

Ubuntu

Shiftfs

References · 26

• 🔥 https://github.com/synacktiv/CVE-2021-3492 · Exploit
• https://security-tracker.debian.org/tracker/CVE-2021-3492 · Vendor Advisory
• https://zerodayinitiative.com/advisories/ZDI-21-422 · Security Note
• https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/focal/commit/?id=25c891a949bf918b59cbc6e4932015ba4c35c333 · Vendor Advisory
• https://ubuntu.com/security/CVE-2021-3493 · Vendor Advisory
• https://ubuntu.com/security/notices/USN-4915-1 · Vendor Advisory
• https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/focal/commit/?id=8fee52ab9da87d82bc6de9ebb3480fff9b4d53e6 · Vendor Advisory
• https://ubuntu.com/security/CVE-2021-29154 · Vendor Advisory
• https://ubuntu.com/security/notices/USN-4917-1 · Vendor Advisory
• https://ubuntu.com/security/CVE-2021-3492 · Vendor Advisory
• https://bdu.fstec.ru/vul/2021-04860 · Security Note
• https://cve.org/CVERecord?id=CVE-2021-3492 · Security Note
• https://osv.dev/vulnerability/USN-4917-1 · Vendor Advisory
• https://osv.dev/vulnerability/CVE-2021-3492 · Vendor Advisory
• https://osv.dev/vulnerability/UBUNTU-CVE-2021-3492 · Vendor Advisory