CVE Vulnerabilities

CVE-2020-15859

Use After Free

Published: Jul 21, 2020 | Modified: Sep 23, 2022
CVSS 3.x
3.3
LOW
Source:
NVD
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
CVSS 2.x
2.1 LOW
AV:L/AC:L/Au:N/C:N/I:N/A:P
RedHat/V2
RedHat/V3
3.8 MODERATE
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:L
Ubuntu
MEDIUM

QEMU 4.2.0 has a use-after-free in hw/net/e1000e_core.c because a guest OS user can trigger an e1000e packet with the datas address set to the e1000es MMIO address.

Weakness

Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code.

Affected Software

Name Vendor Start Version End Version
Qemu Qemu 4.2.0 (including) 4.2.0 (including)
Red Hat Enterprise Linux 8 RedHat virt-devel:rhel-8050020211001230723.b4937e53 *
Red Hat Enterprise Linux 8 RedHat virt:rhel-8050020211001230723.b4937e53 *
Qemu Ubuntu bionic *
Qemu Ubuntu esm-infra-legacy/trusty *
Qemu Ubuntu focal *
Qemu Ubuntu groovy *
Qemu Ubuntu trusty *
Qemu Ubuntu trusty/esm *
Qemu Ubuntu upstream *
Qemu Ubuntu xenial *
Qemu-kvm Ubuntu precise/esm *

Extended Description

The use of previously-freed memory can have any number of adverse consequences, ranging from the corruption of valid data to the execution of arbitrary code, depending on the instantiation and timing of the flaw. The simplest way data corruption may occur involves the system’s reuse of the freed memory. Use-after-free errors have two common and sometimes overlapping causes:

In this scenario, the memory in question is allocated to another pointer validly at some point after it has been freed. The original pointer to the freed memory is used again and points to somewhere within the new allocation. As the data is changed, it corrupts the validly used memory; this induces undefined behavior in the process. If the newly allocated data happens to hold a class, in C++ for example, various function pointers may be scattered within the heap data. If one of these function pointers is overwritten with an address to valid shellcode, execution of arbitrary code can be achieved.

Potential Mitigations

References