medium
6.2
CWE
476
Advisory Published
Updated

CVE-2020-29571: Null Pointer Dereference

First published: Tue Dec 15 2020(Updated: )

An issue was discovered in Xen through 4.14.x. A bounds check common to most operation time functions specific to FIFO event channels depends on the CPU observing consistent state. While the producer side uses appropriately ordered writes, the consumer side isn't protected against re-ordered reads, and may hence end up de-referencing a NULL pointer. Malicious or buggy guest kernels can mount a Denial of Service (DoS) attack affecting the entire system. Only Arm systems may be vulnerable. Whether a system is vulnerable depends on the specific CPU. x86 systems are not vulnerable.

Credit: cve@mitre.org

Affected SoftwareAffected VersionHow to fix
debian/xen
4.11.4+107-gef32c7afa2-1
4.14.6-1
4.14.5+94-ge49571868d-1
4.17.1+2-gb773c48e36-1
4.17.2+55-g0b56bed864-1
Xen xen-unstable>=4.4.0<=4.14.0
Debian=10.0
Fedora=32
Fedora=33

Remedy

https://xenbits.xenproject.org/xsa/advisory-359.html

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Reference Links

Frequently Asked Questions

  • What is the severity of CVE-2020-29571?

    CVE-2020-29571 has been rated as high severity due to its potential impact on system stability and security.

  • How do I fix CVE-2020-29571?

    To fix CVE-2020-29571, update the Xen package to a version that includes the patch for the vulnerability.

  • What versions of Xen are affected by CVE-2020-29571?

    CVE-2020-29571 affects Xen versions 4.4.0 up to but not including 4.14.0 and other specified versions.

  • Is CVE-2020-29571 exploitable remotely?

    CVE-2020-29571 may be exploitable remotely in certain configurations, increasing its risk profile.

  • What should I do if I can't update Xen to fix CVE-2020-29571?

    If you cannot update Xen, consider implementing additional security measures or isolating the affected systems to mitigate risk.

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